Someone who is liked by many and/or smart and/or sporty. Popular people like to dress with the day, being new and modern.
Despite regular superstitions, there is not usually only one group. There are many.
They are not sluts or the first to lose their virginity in school. They don't say the word 'like' every other word. Most are average to smart and mostly enjoy everybody's presence except people who feel they are 'targeted' and are unfair to them.
Movies such as Mean Girls are untrue and stupid. They portray popular people as stupid, slutty, bitches who always diss other people who are 'fat' or 'nerdy'.
In conclusion, popular people can sometimes be mean. But don't you go around saying "OmG TH3Y aRe lIEk CALlIng Me PhAt!!!1!!!111 leTS H@+3 tEHM 4EvER!!!11!11one"
Person 1: Oh, I love Anne!
Person 2: I dunno, shes a popular...
Person 1:...*sigh* And have you ever, I dont know, met Anne?
Person 2: No...
Anne: Hey guys! What to hang out after school with some of my buddies?
Person 2: No way! Ur liek a popular!!11!one
Person 2: Whatever. Im going cuz shes unbeleiveably nice and smart and funny. Cya.