You use passwords to log into websites and services, and since there are so many of them, it’s hard to remember them. It’s a bad idea to use the same password for different websites, because if one site is compromised, hackers will have an email address and password that they can try on other sites. Because of this, you need to ensure that your passwords are different for every website and app, and that they are hard to crack. (An episode of the Intego Mac Podcast talks about password strategies.)
Your Macs and iOS devices have a “keychain,” which is an encrypted file that stores your logins, passwords, and some other information. This file syncs via iCloud, so you can use the same passwords on all your devices. Here’s how Apple’s iCloud keychain works.
Read the rest of the article on The Mac Security Blog.