Have you ever entered the password for your Mac instead of that for your Apple ID? This should help make it clearer which you need to use.
Why do I have to enter my keychain password every time my Mac starts or restarts?
Can I change password entry dialogs to show the correct characters instead of blobs?
When I set up my iPad WiFi, it asks for a password and a user name. How can I find out what my user name is?
Businesses are often built on trust, and one of the most fundamental elements of trust must be in the accuracy of the data on your Mac. How should you ensure that your files remain true and correct?
Everywhere that you go you need user names, passwords, and other means of proving your identity. In OS X and iOS these are normally stored in a keychain.