oh boy - the different answers you could get for this question! Here are some reasons as I see them: they have dry and/or chapped lips; nervousness; trying to be "sexy"; have some kind of food or drink on their lips and are licking it off; it could be an unconscious habit...
Everybody bites their lip.
Yes, usually they are.
When your talking they will look at your lips or they will lick their lips or bite their lower lip.
Boys generally kiss girls by applying their lips to a girls and having a puckering motion to imply a kiss.
Well first I hope you didn't bite a girls face but if you are talking about lips I would say flavored lipgloss, Chapstick, or lip balm
by erotically grabbing their hips and bringing them close to you perky lips, then in a swooping motion ferociously lock lips with his neck
Some do, some do not. Depending on the girl
Their lips and skin are so soft and silky.
Once you have reached puberty, kissing on the lips is enjoyable. i have no clue?
When guys bite their lips & licks their lips, it gives girls a bit of a turn on.
So they can lick it off their faces and lips and then proceed to make out with them.
This could be because he likes your body, and likes you as his.