A tripcode is a way to anonymously distinguish your posts without registering.
To use a tripcode, type Alias#Password into the name/alias field when you post. Your password will not be saved. A character string based on your password will be appended to the end of your name.
For example Shark#AwesomeSauce would yeild Shark!2jZS8mTztI.
This will protect from people pretending to be you, and prove that you are the same poster.