This document summarizes the process of 2-D gel electrophoresis used to separate proteins. It begins with an introduction explaining that 2-D gel electrophoresis couples isoelectric focusing in the first dimension based on isoelectric point and SDS-PAGE in the second dimension based on molecular mass. The document then covers the principles, processes, and techniques involved in isoelectric focusing, SDS-PAGE, blotting, and concludes by discussing the applications and references for 2-D gel electrophoresis.