Password Managers are applications or websites that will store your passwords for you. They encrypt the information, and you use a single master password to access all of your other passwords. You should have a different password for every website, so a password manager helps you keep track of all these passwords, and makes it so you only have to remember the one master password.
KeePass is a free and open source password manager that can be installed on any computer or even on a USB drive. It works with Windows 98 and newer versions of Windows. KeePass has also been reviewed for accessibility and received a strong thumbs up for its use with screen readers.
KeePassX (Mac OS X and Linux)
KeePassX is a free and open source implementation of KeePass. It does not support many of the advanced features of KeePass, but it does have native clients for Mac OS X and Linux. For most purposes KeePassX is a seamless replacement for KeePass.
LastPass is a free browser-based, cross-platform password manager. It can run as a browser extension in most browsers or as a webpage in any browser. LastPass has both a free version and a paid/premium version. The premium version primarily offers clients for mobile devices. You can compare the features found in the free and premium versions. If you do choose to to purchase the premium version, you can use the following URL to receive an 18 month subscription for the price of a 12 month subscription ($12).