This emoticon literally means "heart" since that is what it looks when viewed sideways. In IM language though, it's a less serious way of saying somebody you "
love" them, or at least "care for" them. Even if you do really "
love" somebody, you don't want to say it every minute and every
day -- it gets old and may even scare him or her. So, use "<3" for normal every day conversations, reserving "
love" during the times you really want the other to know you mean it.