Cosplay: Japanese term short for "costume play." The act of dressing up in costume as favorite characters from anime, video games, movies, music, etc.
For us, cosplay is more than just "costume play". We have met so many wonderful people through the hobby. In fact, we (Pixiekitty and Neon Genocide) met each other at Otakon 2002 for the very first time! Each time we go to a convention, we look forward to seeing our many friends and meeting new ones!
It's also a very rewarding way to express creativity, because you get put your work on public display by wearing it. You get to meet the people that appreciate your work first hand, and discuss your common interests.