Does anyone know what a mary-sue?

A Mary Sue is supposed to be a character that a writer may describe as perfect in all ways.

A Mary Sue may;
1) Be beautiful.
2) Be flawless; no evident personality traits that readers can find.
3) Have one person or mais be in amor with her.
4) May be vaguely similar to the author/writer, this character may appear as the writer literally putting themselves in the story.
5) The character is well-liked por a majority of the people.
6) The character does no wrong, and if she (or he, there can be a male Mary Sue known supposedly as Gary Stu) does do something evidently wrong, there's always a good excuse for it.
7) The character is always the huge hero in the end.

Traits like that.

A writer supposedly creates a Mary Sue when he/she is too attached to his/her main character in the story.

It's supposed to be greatly damaging to the story the Mary Sue is in.

I personally don't give too much thought on Mary Sues, but I admit I do try to not give my characters these traits, or if I have to give the character one of the traits above I make sure it's that trait and only that trait.

Well, I hope this helps you out.