In public key cryptographyDEF, each person needs two keys. One is the private key, one is the public key. The private key must be kept secret at all costs. Usually, these are stored on the hard drive in a private location or on a floppy disk that isn't left lying around. If you plan on using PGP for any type of seriously secretive communication, you need to make sure no-one can get your secret key file.
The public and private keys are mathematically related in a way that what is encoded with the one is decodable with the other, but by no other (practical) means. If you actually want to learn more about the math, see the links on this site.
Encrypting is done using the recipient's public key, whereas signing is done using one's own secret key.
You should attempt to get your public key personally to all parties who will be wanting to use it so they can trust it and sign it.
This page is a part of Mike's PGP Page.
All information from this site gathered in my own research and experience.
This page is © Copyright 1998, Michael T. Babcock.
E-mail me if you have questions or comments.