In the context of casual conversations over the Internet, the occasional typo can probably be forgiven. That said, it pays to be as clear and umambiguous as possible, regardless of the form of the communication that you are using. Two such words that seem to get mixed up on a fairly regular basis are roll and role. Only one letter is different, but these two words have vastly different meanings.
Roll can be used either as a verb or as a noun. As a verb, to roll means to move by turning or rotating. For example, you could say that you are rolling a ball down the hill.
As a noun, a roll is a typically a cylindrical object of some kind. You can think of a sushi roll as a good example. You might also know about the honor roll at a school. This might not make intuitive sense, but think about this way: the list of students is traditionally written on a scroll of paper and this is rolled up.
Role is a noun meaning a character or a function. For example, you could say that Steve Carell plays the role of Michael Scott on The Office. You could also talk about the role of government in public healthcare or the role the Nintendo Wii plays in your leisure life.
I hope that clears up any confusion. If you have any grammar questions, feel free to pose them through the comment form below. Who knows? Maybe I’ll choose your question to feature in a future Grammar 101 blog post.