I really don't get when I'm supposed to use everybody/everyone/anybody/anyone. And it has been bothering me for quite some time, so I'm finally asking you guys. What's the difference?
Well for a definition from dictionary.com. Everybody: every person. Everyone: every person; everyone. They mean the same thing.
The difference between everyone and anyone is this: Everyone means what colorthemap said. "Everyone attended the party" equals "All the people attended the party." Anyone/anybody both mean any unspecified person. "Anybody can join this forum" equals "This person or that person or any person in the world can join this forum."
What about the grammar? "Everyone is wearing hats." OR "Everyone are wearing hats." OR "Everyone is wearing a hat." "Everybody is going to the prom." OR "Everybody are going to the prom." Are these considered singular or plural? "Everybody is going to the prom" seems right to me, meaning that "everybody" is singular. But "Pass these flyers out to everybody so that they will know the location of the prom" also seems right, and in that, "everybody" is plural. Weird.
I'd like to think everybody is more informal(as close as it comes to in English.) whereas everyone would be more formal. So if it were me I'd have: Everyone in narrative. Everybody in dialog.