Texer - Aops !!top!!

Here’s a concise guide covering what it is, how to access it, and basic syntax. TeXer is AoPS's built-in LaTeX editor and previewer. It lets you write mathematical expressions and see exactly how they will render in forum posts, messages, or contest solutions—without posting first.

It looks like you're asking about on the Art of Problem Solving (AoPS) website. texer aops