In one sentence: A master password is the one password that unlocks your password manager.
Why it matters: It protects all your other passwords, so it needs to be long and used nowhere else. Four or more random, unrelated words make a good one. Official advice varies: some say at least three words, and US CISA says four to seven. Some password managers cannot recover it if you forget it. Some services call it a “primary password”.
One thing to do: Choose a new master password made of four or more random words, and never reuse it. If you write it down, keep the paper safe.
Related terms: password manager, passkey, recovery code
Learn more: What Is a Password Manager, and How Do You Choose One?
Checked: 25 Oct 2026. Settings screens change. If yours looks different, search the company's help page.
