Muslims: Do we know what Prophet Mohammed looks like even though you are forbidden to make an image of him?

I was just wondering. I am not trying to insult your Faith in any way, but I read that you were not allowed to draw or make any image of Hims or Allah. So I looked on Google Images for ' Prophet Mohammed' and there came up some images that he might look like? I did not attach a link to the pictures because I didn't know if that would be considered haram to you and if you accidentaly saw one of them I don't want to be the person responsible of you performing Haram. Is it a sin to make an image of Him? And if it is why would people post on Google paintings and pictures of him?