Short, easy to understand explanation of GPG/PGP for nontechnical people?

Solution 1:

Why Use PGP? -- probably fits your size.

PGP is useful for two things: 1. Privacy and Security, and 2. Authenticity.
By privacy, I mean that you can prevent people from seeing things. For example, you can encrypt an email to someone, or encrypt a file with a list of passwords.
By Authenticity, I mean that you can ensure a message was sent/written by the person you think it was, and that it wasn't modified by a third party. Of course, these two can be combined.

Would also recommend -- GnuPG FAQ Advanced Topics for a quick read

HowTo and tutorial references afterwards,

• GPG Signing: Traditional vs. PGP/Mime -- good short reference
• The Ubuntu documentation -- GnuPrivacyGuardHowto
• GPG/PGP Basics
• Gnu Privacy Guard tutorial
• PGP tutorial
• Secure Key Generation [DRAFT]
• Quick reference Mini Tutorial -- (seem to have changed to this)

Take your pick on a comfortable read.