Hi, I have been reading up on the Seperating Axis Theorem, and I have some questions.

http://www.codezealot.org/archives/55

The article does a great job on explaining what the SAT is, but I want to know what axes is the author referring to exactly. Would I use the X and Y axes or make my own arbitrary axes?

Also the author talks about "flipping the coordinates and negating one." in orderto get the normals for the edges. What did he mean by that?

Thanks in advance.