To build a web application, we need to... create a user, sign into that user, save private data, publish content, send private messages, and have group conversations. Phew! That is a lot.

The most important piece is first creating user accounts. Unfortunately, a username/password combo is not very secure. We need something better.

During the Cold War a new type of security was invented. It is similar to a username/password, but imagine instead having to memorize the first thousand digits of PI! Having a password that long would take a hacker one hundred years to break. This is why it is secure and it is called public/private key cryptography.

However, your users would probably get really confused with that. So how can we let them keep their own password... but still have real security? Well, we take their normal password and mix with other information. The end result is long and complicated, creating a secure account for our users to sign into.

We'll go into more details on how this works in our next video.