FURVERT!

2011 anthro beret biped canid canine canis clothing cockiestspaniel domestic_dog dream german_shepherd hat headgear headwear herding_dog keith_(redfield007) male mammal military monochrome pastoral_dog sitting sketch soldier solo uniform warrior

2011 anthro australian_shepherd canid canine canis clothed clothing cockiestspaniel digitigrade domestic_dog english_text fully_clothed herding_dog hybrid jackal luke_skywalker male mammal model_sheet multiple_poses nude pastoral_dog pose robe sheepdog smile solo star_wars tail text topless underwear

alcohol anthro beverage black_hair black_nose blue_eyes canid canine canis claws clothing collar comic domestic_dog dress female female/female food german_shepherd hair herding_dog mammal pastoral_dog plant potato rakai sabine_(artist) tail vegetable watermark wine

angel_(lady_and_the_tramp) belly big_belly bodily_fluids bolt_(bolt) bolt_(film) canid canine canis dafuq_did_i_just_read disney domestic_dog duo female feral fetus german_shepherd herding_dog internal lactating lady_and_the_tramp male mammal milk mixed_breed nipples pastoral_dog pomsky pregnant text unknown_artist wall_of_text

animal_genitalia anthro atty_(atty) balls barefoot biped blonde_hair border_collie canid canine canis clothing collie digitigrade domestic_dog facial_piercing feet fully_sheathed genitals hair herding_dog hi_res kerchief lip_piercing male mammal nude pastoral_dog piercing sheath sheepdog snakebite_piercing solo tail teil

2012 4_toes anatomically_correct anatomically_correct_genitalia anatomically_correct_vulva animal_genitalia animal_vulva balls bodily_fluids canid canine canine_genitalia canine_vulva canis conditional_dnp cum cum_in_vagina cum_inside domestic_dog duo erection eyes_closed feet female female_penetrated feral feral_on_feral from_behind_position genital_fluids genitals german_shepherd herding_dog hindpaw hunting_dog knot lying male male/female male_penetrating male_penetrating_female mammal nude on_side outside pastoral_dog pawpads paws penetration penile penile_penetration penis penis_in_vagina psy101 raised_leg rip_(psy101) saluki sex sighthound spread_legs spreading suki_(psy101) tail toes vaginal vaginal_penetration vulva

1:1 afevis_(character) against_surface against_wall anal anal_penetration anthro anthro_on_anthro anthro_penetrated anthro_penetrating anthro_penetrating_anthro canid canine canis dipstick_tail domestic_dog duo eyes_closed fur german_shepherd herding_dog hi_res husky huttser male male/male male_penetrated male_penetrating male_penetrating_male mammal markings nordic_sled_dog nude nuzzling pastoral_dog penetration sex simple_background spitz stand_and_carry_position standing standing_sex tail tail_markings virtyalfobo

afevis_(character) anthro balls bodily_fluids butt butt_markings canid canine canis domestic_dog dydoe_piercing ear_piercing erection footprint genital_fluids genital_piercing genitals german_shepherd glans_piercing harlem herding_dog heterochromia hi_res knot looking_at_viewer male mammal markings nude pastoral_dog pawprint pawprint_tattoo penis penis_piercing piercing precum presenting simple_background solo spread_legs spreading tail tattoo

2012 anthro biped blonde_hair blue_background bottomwear boy_shorts breasts brown_body brown_fur brown_tail butt canid canine canis claws clothed clothing clothing_lift digital_media_(artwork) dirtybird domestic_dog dress dress_lift eyes_closed fangs female fully_clothed fur german_shepherd gown hair herding_dog lace lisa_(lisa87) mammal nightgown open_mouth panties panty_shot pastoral_dog raised_tail rear_view red_bottomwear red_clothing red_topwear simple_background solo standing stretching tail tail_under_skirt tail_upskirt teeth tongue topwear underwear upskirt yawn

all_fours anal anal_penetration anatomically_correct anatomically_correct_genitalia anatomically_correct_penis animal_genitalia animal_penis anthro anthro_on_feral anthro_penetrated bestiality bioluminescence biped black_body black_claws black_fur black_pawpads blue_body blue_fur bodily_fluids brown_body brown_fur canid canine canine_genitalia canine_penis canis claws countershading cum cum_on_ground cum_while_penetrated cumshot digitigrade doggystyle domestic_dog duo ejaculation erection feral feral_penetrating feral_penetrating_anthro flynx-flink from_behind_position fur genital_fluids genitals german_shepherd gloves_(marking) glowing glowing_eyes glowing_genitalia glowing_pawpads glowing_penis green_pawpads green_penis hair hands-free herding_dog intraspecies intraspecies_bestiality leg_markings looking_back mako_wolfhardt male male/male male_on_feral male_penetrated male_penetrating male_penetrating_male mammal markings mounting nude open_mouth orgasm pastoral_dog pawpads penetration penile penile_penetration penis quadruped sex socks_(marking) tail tattoo toe_claws tongue tongue_out white_body white_countershading white_fur wolf

2012 anthro australian_shepherd bikini blue_eyes blue_hair breasts buoy canid canine canis chazcatrix clothed clothing detailed_background digital_media_(artwork) domestic_dog female hair herding_dog hyacinth_(hyacinth) looking_at_viewer mammal multicolored_hair nipple_outline outside pastoral_dog sea seascape shaded sheepdog skimpy sky smile solo sun swimwear two-piece_swimsuit two_tone_hair water

anthro biped border_collie breasts canid canine canis cockiestspaniel collie domestic_dog female herding_dog hi_res mammal nipples nude pastoral_dog pinup pose sheepdog shepherd shepherd's_crook sitting solo tail

1:1 anal anal_masturbation anal_penetration anthro canid canine canis chibi clothed clothing dessert dialogue dildo domestic_dog duo english_text erection fellatio food fox_(housepets!) genitals herding_dog hi_res housepets! husky ice_cream kerchief king_(housepets!) knot male mammal masturbation multiple_images neckerchief neckwear nialus nordic_sled_dog oral oral_penetration pastoral_dog peanut_butter_(housepets!) penetration penile penis red_clothing red_underwear sex sex_toy sketch sketch_page solo solo_focus spitz text underwear welsh_corgi yellow_clothing yellow_kerchief yellow_neckerchief

black_and_white canid canine canis comic disco domestic_dog door english_text female feral german_shepherd group herding_dog hi_res human humor joke male mammal monochrome pastoral_dog police raised_tail tail text unknown_artist

2012 aidi_dog anthro canid canine canis clothed clothing cloud colored_pencil_(artwork) desert domestic_dog female front_view hi_res karja livestock_guardian_dog looking_at_viewer magic_user mammal melee_weapon molosser moroccan morocco mountain mountain_dog nomad outside painting_(artwork) pastoral_dog polearm sky solo staff tail traditional_media_(artwork) traditional_painting_(artwork) traditional_watercolor_(artwork) walking watercolor_(artwork) weapon

2012 anakuro animal_genitalia animal_penis anthro belly blue_eyes bulge canid canine canine_genitalia canine_penis canis clothed clothing collie coyote crossdressing digital_media_(artwork) domestic_dog duo erection eye_contact fellatio femboy first_person_view freckles genitals gloves hair handwear herding_dog humanoid_genitalia humanoid_penis hybrid_genitalia hybrid_penis knot knotted_humanoid_penis knotted_penis latex legwear licking long_hair looking_at_another looking_at_partner looking_at_viewer male male/male male_penetrated male_penetrating male_penetrating_male male_pov mammal nude oral pastoral_dog penetration penile penis penis_lick ponytail rough_collie sex sheepdog simple_background sketch solo_focus stockings tail thong tongue tongue_out top_pov underwear white_background

anthro canid canine canis child clothing cuddling domestic_dog duo eyes_closed german_shepherd herding_dog hug kado koosh-ball kraze male mammal pastoral_dog standing tail young young_anthro

3:2 aircraft amber_eyes anthro bedroom_eyes big_breasts biped black_nose blonde_hair breasts building butt canid canine canis colored domestic_dog female female_anthro furball german_shepherd hair half-closed_eyes helicopter hera_(hera) herding_dog leaning leaning_backward looking_at_viewer macro macro_anthro macro_female mammal narrowed_eyes nipples pastoral_dog seductive smile solo tail vehicle

anthro avian bailey_(housepets!) beak bino_(housepets!) canid canine canis collar collar_only cousins_(lore) domestic_dog domestic_ferret feathered_wings feathers female flat_chested fox_(housepets!) group gryphon herding_dog housepets! husky keene_(housepets!) king_(housepets!) kiwaka male male/female mammal mustelid musteline mythological_avian mythological_creature mythology nordic_sled_dog nude pastoral_dog pawpads paws pete_(housepets!) romantic romantic_couple scarf sitting spitz standing tail true_musteline weasel welsh_corgi wings

2012 amputation australian_shepherd blood bodily_fluids breasts candy_gore canid canine canis collar danji-isthmus digital_media_(artwork) digital_painting_(artwork) dismemberment dokuga domestic_dog electricity female gold_blood gore herding_dog lightning mammal multi_nipple nipples nude painless_gore painting_(artwork) pastoral_dog sheepdog solo surrealism

2012 anthro antlers black_hair breasts canid canine canis domestic_dog dominant duo erection eyes_closed female female_penetrated fur genitals hair heart_symbol herding_dog horn knot larger_dom larger_male lying male male/female male_penetrating male_penetrating_female mammal narcotic_sprinkles nude on_back pastoral_dog penetration penile penile_penetration penis penis_in_vagina sex size_difference smaller_female smaller_penetrated tail unknown_species vaginal vaginal_penetration welsh_corgi yellow_body yellow_fur

2012 anthro balls big_breasts black_hair bottomwear bottomwear_down breast_grab breasts canid canine canis chair_position clothed clothing cross cross_necklace domestic_dog duo erection eyes_closed eyewear felid feline female female_penetrated from_behind_position genitals grope hair hand_on_breast hat headgear headwear herding_dog jewelry lynx male male/female male_penetrating male_penetrating_female mammal monocle narcotic_sprinkles necklace nude pants pants_down partially_clothed pastoral_dog penetration penile penile_penetration penis penis_in_vagina sex spread_legs spreading top_hat vaginal vaginal_penetration vulva welsh_corgi

anthro black_border blusong border border_collie bottomless butt canid canine canis clothed clothing collie dildo domestic_dog female genitals herding_dog mammal masturbation pastoral_dog penetration sex_toy sheepdog shirt solo topwear toying_self vaginal vaginal_masturbation vaginal_penetration vibrator vulva wet

3:2 anthro anthrofied blush bolt_(bolt) bolt_(film) breasts canid canine canis collar digital_drawing_(artwork) digital_media_(artwork) disney domestic_cat domestic_dog duo exhausted felid feline felis female german_shepherd herding_dog interspecies looking_pleasured lying male male/female mammal mittens_(bolt) monochrome nipples nude on_back on_bottom on_top pastoral_dog reverse_cowgirl_position sex simple_background tail thefuckingdevil tongue tongue_out white_background

2012 after_sex anthro anus biped black_body black_fur black_nose bodily_fluids breasts brick brick_wall brown_body brown_fur brown_nipples brown_theme butt canid canine canis carmen_herrera clitoris clothed clothing cum cum_covered cum_drip cum_everywhere cum_in_ass cum_in_hair cum_in_mouth cum_in_vagina cum_inside cum_on_belly cum_on_body cum_on_breasts cum_on_butt cum_on_chest cum_on_clothing cum_on_face cum_on_feet cum_on_hand cum_on_leg cum_on_nipples cum_on_tail cum_on_vulva cum_taste digital_media_(artwork) domestic_dog dripping excessive_cum excessive_genital_fluids feet female finger_fetish finger_in_mouth finger_play fingers footwear footwear_only fur fur_markings genital_fluids genitals german_shepherd gloves_(marking) graffiti hair half-closed_eyes hand_behind_head herding_dog humanoid_genitalia humanoid_vulva leg_markings legwear legwear_only long_hair looking_at_viewer mammal markings messy mostly_nude multicolored_body multicolored_fur narrowed_eyes navel nipples open_mouth pastoral_dog pink_hair pose presenting presenting_vulva public purple_eyes red_clothing red_legwear sitting socks socks_(marking) socks_only solo spread_legs spreading statik tail thigh_highs thigh_socks toeless_footwear toeless_socks translucent translucent_clothing translucent_legwear two_tone_body two_tone_fur vulva wall_(structure) watermark

all_fours anal anal_penetration animal_genitalia animal_penis anthro anthro_on_feral anthro_penetrating anthro_penetrating_feral balls bandage bestiality biped bodily_fluids canid canine canine_genitalia canine_penis canis collar cum cum_inside digitigrade dipstick_tail domestic_dog duo erection feral feral_penetrated genital_fluids genitals german_shepherd gloves_(marking) hair handjob herding_dog hyena interspecies knot leg_markings looking_back male male/male male_penetrated male_penetrating male_penetrating_male mammal markings namarx7 nude open_mouth orgasm partners pastoral_dog penetration penile penis quadruped raised_tail romantic romantic_couple sex simple_background socks_(marking) spotted_hyena tail tail_markings thick_thighs tongue tongue_out

2012 all_fours animal_genitalia animal_penis anus balls bed black_body black_fur black_nose bodily_fluids brown_body brown_fur canid canine canine_genitalia canine_penis canis collar conditional_dnp cum cum_in_vagina cum_inside dipstick_tail doggystyle domestic_dog dripping duo erection eyes_closed feet female female_penetrated feral feral_on_feral fox from_behind_position fur furniture genital_fluids genitals german_shepherd herding_dog hindpaw interspecies knot male male/female male_penetrating male_penetrating_female mammal markings metal_collar nelya_rhys_(character) nude pastoral_dog pawpads paws penetration penile penile_penetration penis penis_in_vagina psy101 rip_(psy101) sex standing tail tail_markings tan_body tan_fur tongue tongue_out vaginal vaginal_penetration vulva

1:1 2012 animal_genitalia animal_penis anthro balls biped black_nose bodily_fluids canid canine canine_genitalia canine_penis canis cum dershep digital_media_(artwork) domestic_dog dripping erection fur genital_fluids genitals german_shepherd herding_dog kneeling knot male mammal nude pastoral_dog paws penis purple_body purple_fur purple_penis sheath smile solo tail tan_body tan_fur wintersnowolf

2012 anthro balls bdsm bloo blue_eyes bodily_fluids bondage bound breasts canid canine canis claws cum cum_in_vagina cum_inside digitigrade domestic_dog dominant dominant_male duo erection eyes_closed feet female female_penetrated from_behind_position genital_fluids genitals german_shepherd herding_dog hindpaw larger_dom larger_male leash lying male male/female male_penetrating male_penetrating_female mammal muzzle_(object) muzzled nipples nude on_side one_eye_closed open_mouth pastoral_dog paws penetration penile penile_penetration penis penis_in_vagina raised_leg rope rope_muzzle sex size_difference smaller_female smaller_penetrated submissive submissive_female tail tongue tongue_out vaginal vaginal_penetration vulva

16:9 all_fours anal anal_orgasm anal_penetration anthro anus backsack balls bed bodily_fluids brother_(lore) brothers_(lore) brown_body brown_fur butt canid canine canis circumcised close-up countershading cum cum_in_ass cum_in_mouth cum_inside cum_on_butt cum_on_face cumshot digital_media_(artwork) doggystyle domestic_dog dream_and_nightmare dripping ejaculation erection eyes_closed feet fellatio flaccid from_behind_position fur furniture genital_fluids genitals german_shepherd group group_sex hair hands-free herding_dog hi_res humanoid_genitalia humanoid_penis inside kneeling male male/male male_penetrated male_penetrating male_penetrating_male mammal night nude on_bed open_mouth oral orgasm pastoral_dog penetration penile penis precum procyonid raccoon rave_raccoon sex sibling_(lore) sky spitroast star starry_sky tail threesome tongue trio white_hair widescreen

2012 after_sex afterglow amber_eyes anthro big_breasts blue_eyes blush breasts canid canine canis cassie_collins collie domestic_dog duo eye_contact female fossilizedart fox grey_fox herding_dog kneeling looking_at_another looking_back lyle_kitsune male male/female mammal nipples nude open_mouth pastoral_dog reach_around rough_collie sex sheepdog simple_background tail teeth urocyon wide_hips

2012 2d_animation accessory after_orgasm anal anal_penetration animal_genitalia animated anthro anus backsack balls biceps big_balls blue_eyes bodily_fluids bouncing_balls bouncing_penis brown_body brown_fur bus_stop butt canid canine canis collie cum cum_in_ass cum_inside deep_penetration detailed_background digital_media_(artwork) domestic_dog dominant dragon duo erection exhibitionism eyebrows eyes_closed flash from_behind_position front_view fur genital_fluids genitals green_eyes herding_dog horn interactive interspecies jasonafex kellogg knot larger_dom larger_male leaking looking_down looking_pleasured loop low-angle_view male male/male male_penetrated male_penetrating male_penetrating_male mammal motion_tweening muscular muscular_anthro muscular_male mythological_creature mythological_scalie mythology necktie neckwear nude open_mouth outside outside_sex pastoral_dog penetration penis perineum public public_nudity public_sex razr rough_collie scales scalie sex shaded sheath sheepdog size_difference sky smaller_male snout sound spread_legs spreading teeth urosteges ventral_scales white_body white_fur white_scales worm's-eye_view

2012 4_toes anthro anthro_on_anthro barefoot black_nose blue_body blue_fur border_collie boxers_(clothing) briefs brown_body brown_eyes brown_fur brown_nose canid canine canis clothed clothing collie domestic_dog duo ear_piercing eyes_closed eyewear feet footprint fur furgonomics glasses herding_dog hi_res hug kissing licking male male/male mammal markings michael_collin multicolored_body multicolored_fur one_eye_closed pandapaco pastoral_dog pawprint pawprint_(marking) paws piercing robbie_(rotten_robbie) romantic romantic_couple sheepdog simple_background smile standing tail tail_clothing toes tongue tongue_out topless two_tone_body two_tone_fur underwear underwear_only white_background white_body white_fur wolf young young_anthro

5_fingers anthro anus athletic athletic_anthro athletic_male back_groove backsack balls bare_back black_and_white border_collie canid canine canis collie domestic_dog fingers fluffy fluffy_tail genitals herding_dog light_body light_hair light_tail lopped_ears lying male mammal michael_collin monochrome nude on_front open_mouth pastoral_dog rallyreki rear_view sheepdog shoulder_blades simple_background snout solo tail tongue tongue_out

1:1 2d_animation 3_toes animated animated_gif anthro barefoot big_eyes big_head biped border_collie bottomwear brown_body brown_eyes brown_fur canid canine canis clothed clothing collie domestic_dog eyewear feet footprint fully_clothed fur glasses grass herding_dog looking_up low_res male mammal markings michael_collin night outside pants pastoral_dog pawprint pawprint_(marking) pince-nez plant sheepdog short_playtime sitting sky solo star starry_sky sweater toes toony topwear turtleneck twinkle white_body white_fur yannlian young young_anthro young_male

abs anthro bottomwear brown_eyes canid canine canis chest_tuft clothed clothing domestic_dog fur german_shepherd herding_dog male mammal muscular muscular_anthro muscular_male nemulas open_clothing open_shirt open_topwear pants pastoral_dog pecs pose sarustreeleafwolf shirt shorts solo tail topwear tuft wolf

2012 anal anal_penetration animal_genitalia animal_penis anthro ass_up athletic bent_over bodily_fluids brown_body brown_fur butt butt_grab canid canine canine_genitalia canine_penis canis carrot_(artist) chair character_request claws clenched_teeth cum digitigrade domestic_dog duo erection feet from_behind_position fur furniture genital_fluids genitals german_shepherd granite_the_wolf hand_on_butt herding_dog hi_res hindpaw knot male male/male male_penetrated male_penetrating male_penetrating_male mammal muscular nude open_mouth pastoral_dog paws penetration penis precum red_penis sex simple_background spread_legs spreading standing standing_sex tail teeth wolf

2012 anthro back_boob biped blue_eyes border_collie breasts butt canid canine canis collie digital_media_(artwork) dipstick_tail domestic_dog eliza_edington feet female hair herding_dog hindpaw looking_at_viewer mammal markings mistresssparkles nude pastoral_dog paws pinup pose rear_view sheepdog sitting solo tail tail_markings tricolor wide_hips yokozuwari

anthro back_boob border_collie breasts canid canine canis collie dipstick_tail domestic_dog feet female herding_dog hindpaw mammal markings mistresssparkles nude pastoral_dog paws rear_view sheepdog smile solo tail tail_markings

1:1 anthro big_breasts blonde_hair bodily_fluids bottomwear bottomwear_down breasts canid canine caninu canis clothed clothing collie cum cum_in_vagina cum_inside cyberconnect2 domestic_dog duo erection eyewear female female_penetrated genital_fluids genitals glasses hair herding_dog human human_on_anthro interspecies little_tail_bronx long_hair male male/female male_penetrating male_penetrating_female mammal merveille_million messy nipples nude orgasm pants pants_down partially_clothed pastoral_dog penetration penile penile_penetration penis penis_in_vagina sex sheepdog solatorobo tail tenseiani third-party_edit tongue tongue_out vaginal vaginal_penetration

2012 action_pose australian_shepherd canid canine canis collar digitigrade dokuga domestic_dog female feral herding_dog heterochromia iexploded looking_at_viewer mammal orange_eyes pastoral_dog pose purple_eyes quadruped sheepdog simple_background solo tail

2012 australian_shepherd black_bars canid canine canis collar detailed_background digitigrade domestic_dog female feral herding_dog heterochromia iexploded letterbox mammal open_mouth orange_eyes pastoral_dog purple_eyes quadruped sheepdog smile solo sun sunset tail tongue tongue_out

2012 ambiguous_gender australian_shepherd canid canine canis collar digital_media_(artwork) digital_painting_(artwork) digitigrade dokuga domestic_dog falvie feral herding_dog heterochromia mammal open_mouth orange_eyes painting_(artwork) pastoral_dog purple_eyes quadruped sheepdog simple_background smile solo tongue tongue_out white_background

2012 2:3 abs anthro balls biceps big_penis blue_eyes bodily_fluids bruki canid canine canis comic dialogue domestic_dog dripping duo english_text erection eyes_closed fellatio fur genital_fluids genitals german_shepherd green_eyes herding_dog hi_res licking male male/male male_penetrated male_penetrating male_penetrating_male mammal multiple_scenes muscular nipples nude oral oral_penetration pastoral_dog pecs penetration penile penis penis_lick precum profanity saliva sex tail text thick_penis tongue tongue_out vein wolf

2012 2:3 abs anal anal_penetration anthro anthro_on_anthro anus backsack balls bed biceps big_penis blue_eyes blush bodily_fluids bruki butt canid canine canis comic dialogue domestic_dog duo english_text erection eyes_closed fur furniture genital_fluids genitals german_shepherd green_eyes herding_dog hi_res male male/male male_penetrated male_penetrating male_penetrating_male mammal multiple_scenes muscular nipples nude pastoral_dog pecs penetration penis precum profanity saliva sex tail text thick_penis vein

2012 2:3 abs anal anal_penetration anthro anus backsack balls bed biceps big_penis blue_eyes blush bodily_fluids bruki butt canid canine canis comic dialogue domestic_dog duo english_text erection fur furniture genital_fluids genitals german_shepherd green_eyes herding_dog hi_res leaking low-angle_view male male/male male_penetrated male_penetrating male_penetrating_male mammal multiple_scenes muscular nude pastoral_dog pecs penetration penis precum profanity saliva sex tail text thick_penis vein worm's-eye_view

abs anthro bed_sheet bedding canid canine canis clothed clothing domestic_dog duo erection furniture genitals german_shepherd grin harlem herding_dog humanoid_genitalia humanoid_penis lying male male/male mammal markings massage massage_table mastiff molosser muscular muscular_male nipples nude on_back on_table palm_tree pastoral_dog pecs penis pillow pink_penis plant rottweiler smile table topless towel tree

anthro bailey_(housepets!) canid canine canis comic dialogue domestic_dog english_text female flat_chested herding_dog housepets! husky king_(housepets!) male male/female mammal masturbation nordic_sled_dog pastoral_dog phone_sex rick_griffin scarf spitz text third-party_edit url welsh_corgi

2012 anthro biped blue_body blue_border blue_fur border breasts canid canine canis domestic_dog female fur genitals german_shepherd green_eyes herding_dog hi_res iggi jen_(convel) mammal nipples nude pastoral_dog simple_background smile solo standing tail tongue vulva

2012 4_toes banrai black_nose border brown_body brown_fur brown_hair canid canine canis claws colored_pencil_(artwork) crossed_arms domestic_dog feet fur german_shepherd hair herding_dog hindpaw looking_aside lying male mammal nude on_side pastoral_dog pawpads paws purple_eyes rear_view short_hair simple_background smile solo tail toes traditional_media_(artwork) white_background