What is OpenPGP?

When I tried to respond to an e-mail I received using Thunderbird, I had to go through a 10 minute setup for a thing called OpenPGP. Apparently it stands for Pretty Good Privacy http://en.wikipedia.org/wiki/Pretty_Good_Privacy and allows me to encrypt messages I send to people. Only problem is I also have to give them a key and keep a key for myself. I have a file to kill my key if it is compromised and I can make a new one, but mine is good for 5 years if I don't kill it. Other people can also use this and create a key to share with me so they can encrypt stuff to me. It helps the world know that the e-mail was sent from you. It would probably be a nice tool if it wasn't such a pain in the neck. I set it up and told it to leave me alone. If I am still using FireFox in five years I hope I can remember my Keyphrase...