In this increasingly virtual online world, you have to be careful to protect your data. Learn the basics of encoding and encrypting important bits of information, such as passwords, credit card numbers, and even entire messages. Get an overview of what it means to encrypt and decrypt information, as well as some practical examples involving passwords and other data, using PHP's built-in functionality.

Consider how today's world differs from the world of just 20 years ago. Long ago, in the 1980s, encryption was spy stuff -- something you read about in a techno-thriller by Tom Clancy. If somebody wanted to keep a bit of information private, he encrypted the data with a password, a pass phrase, or another basic method.

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