A person (male or female) who constantly has their phone open minute by minute. From right when they wake up, to right before they go to bed. Their phone is like a reusable drug, and you know when someone is addicted. Click, clack, click, click is all you hear from them. Even if they come in contact with the person they are texting, they still text after parting ways for some odd reason.
It makes them feel at ease to have their phone extremely close to them. If their phone is dead or forgotten somehwere, they go into depression and/or a "sleepy" state in which they almost stop talking altogether. Anywhere and everywhere they are texting; even at the most awkward places where you would not be texting, (example: a movie theatre) which is EXTREMELY annoying especially knowing the fact that they aren't even paying any attention to the movie.
You may also notice with avid texters that they pay no attention to anything else except writing their message to the other avid texter. Usually it's described as a zombie or brain dead stage and they are only attentive when the phone is closed. The sad thing is, most phone companies offer "Unlimited Texting" which makes all the avid texters out there go nuts. Also, most phones have "T9 Text" which spells out words for them so they can text pages upon pages of nothing but bullcrap.
Does anyone have a clue of what they are texting? No. Can we find out? No, because if you even touch their phone they will freak out and ask you "what the hell are you doing?" and get very defensive like their phone is a precious diamond.
John: "Hey, Mike, what do you wanna do now?"
Mike: ".....(click, click, clack, click)"
Mike: *Shuts phone* "What?!"
Mike: (Click, click, clack, click)