Question: what does it mean when someone writes in capital letters?
Answer: WRITING ENTIRELY IN BLOCK CAPITALS IS SHOUTING, and it's rude. We've all done it: left the Caps Lock on while typing. But in email etiquette, online chats and/or forum posts, writing in capitals is the online equivalent of shouting. It's rude, so best not to do it unless you really do want to shout at someone.