This has many meanings.
Some common ones are Less than three <3, a sideways heart <3 (normally meaning love), and a face <3.
The < is the eyes/eyebrows, in a.. well, happy position. Kinda. And the mouth, 3, is like an animal mouth. Kinda.
Such as :3, =3, ;3, and so on.
But basically, whether a heart or a happy face, the meaning usually comes out as love or happiness.
Ad more threes and exclamation marks to show that the emotion is more.
I <3 Kitties.
omgz! <333!! Thankyooo!
Less than three <3 and more than one >1
Some people use this as a heart, but those people are wrong. It is clearly a ballsack.
I <3 you (I ballsack you)
When viewed sideways, appears to be the outline of a heart. Used in an expression of love.
I less than three you baby!
Love, or Heart.
I <3 you! or... <3 for Julie!
a annoying way of putting a heart online
mostly used by 15-17 year old girls who have nothing more to do than kiss boys that wear the same pants as them
OMGOMGOMGOMGOMGO MOMGO MOGM i <3 his pants i want to kiss him
A heart. Usually means love.
I <3 you
I love you
love, or more literally "heart"
I <3 you. ( I "heart" you, or I "love" you )
a heart. just sideways
i <3 you. = i heart you.
i </3 you. = i don't heart you.