A hit anime by KyoAni (Silice of Life)
It's about these 4 girls and their normal life in highschool with a rather cutesy artstyle (which causes some folks to mistake them for younger than they actually are; 16 at the start of the manga/show)
All in all it's well done despite a some flaws
Only used mainly Vol1 with bits of 2 and 3
Rushed things into an ending (Unlike KyoAni not to milk something)
Somewhat excessive self references
And the last one I'll save for last.
Konata: Otaku girl with male tastes. She likes games, anime, hentai (Both games and anime) remarking about her friends (Miyuki's bust, Kagami's weight, Tsukasa's moe); she's the show genki girl. Has a tsukkomi/boke (She's the latter) with Kagami. Once as nearly popular as Kagami, it seems to have decreased due to various factors (for one weeaboo-related backlash) Most obvious is despite her age she looks very much like a loli and knows it.
Kagami: The Tsukkomi of the group. She's sensible, nice if a bit cynical. She keeps Konata in line and has an interesting dyanamic (with hints of tsundere) with her that unless balanced out by Miyuki, will take over the whole scene. Konata often bugs her for home work. The most popular LS character (perhaps abnormallly so) Her hobbies are light novels and Shumps. She's regarded as the most normal girl, rather pretty at that; though she worried alot about her weight (Then again seeing what's going on with some Idols, it's not that out there)
Tsukasa: Kagami's faternal twin sister. Good at cooking, but hardly anything else, she's the moeblob type that's just adorable, especially the sounds she makes, making her popular with MAD makers.
Miyuki: The balancer of the group ultimately she keeps the konami dyanamics in line and allows for a more even discussion. She's very smart, athetic, mature (in both body and mind), etc. But is balanced out by clumsiness and airheadedness at times (mainly when reading a book) Out of this 4, she's moderately popular compared to Kagami, especially in doujins despite her H fodder factor (curves, long legs, glasses, pantyhose)
Some of the less main ones
Misao: The most genki girl on the show, best known for her vocal quirks and cute sounds while she's eating. She's best noticed by her tanned skin, yellow eyes, and cute fang. Her and Ayano are friends with Kagami, but it seems Kagami prefers Konata's company. Isn't it said, Misao?
Ayano: Misao's friend who seems really calm. Not much been covered about her as of the material KyoAni used (and that's before their bias is in effect) So other than an informed trait of being scary when angry, she's a background character more or less. Eab1990 is her only real fan.
Yutaka: Konata's younger cousin that's even smaller than her. Pure moe. Her personality is the rather typical moeblob one, though unlike Tsukasa, she seems pretty sharp if naive. ("What is yaoi?") Also rather sickly.
Minami: Tall green haired girl that's best friends with Yutaka. She's a silent sort, but Yutaka understands her perfectly. (The dyanamic is also yuri fodder.) She worries about her bust size.... for the fact she's basically flat (But she makes it work) and the fact she grew up with Miyuki (Who is anything but flat. Due to the yuri potiental and such her and Yutaka get the most screen time out of the first years.
Hiyori: Doujin artist, yuri/yaoi fangirl. She struggles not to captialize off of the prime yuri fodder that occurs. Suprisingly the anime didn't have many scenes of her interacting with Konata (Fellow Otaku); but unlike Konata, her taste is a bit closer to a girl's than a guy's.
Patricia/Patty: Weeaboo exchange student from AMERICA! With all the common traits (Blonde, blue eyed, and a rack that's only 2nd to Miyuki's) She is a rare case of being cute while a weeaboo. Is a yaoi fangirl, which might make some people think about dating one. She also works with Konata at a cosplay cafe.
Soujiro: Konata's dad, novelist, Otaku and lolicon (But he doesn't mind a curvy girl either). He's responsible for how Konata turned out. He's akin to OTers in a few ways, though doujins with him in it might come off as creepy.
Yukari: Miyuki's mother, and the only case of Curvy Moe MILF. She's more immature than her daughter and is often mistaken for her older sister. Prone to being mischevious. It's been said most OTers prefer her to her daughter.
last is KyoAni's Konami emphasis, this combined with their material selection really screwed over many other characters (more will be added at a later time)