In Japanese, the word Gaijin refers to a foreigner, a person who is from "outside". The two chinese characters shown above mean just that: "outside" and "person". The term has also been used in a potentially derogatory way to mean "non-Japanese".
This site is for gaijin of all nationalities (including Japanese) to better understand each other. So sign up and join the rest of us gaijin, and help promote the idea that people are the same whatever their nationality!
Welcome! Yoroshiku!
Want more information? Here's an excellent summary page.