What makes a password strong?
Strength comes from how many guesses an attacker needs, which depends on length and on how many different characters each position can hold. A 20-character password drawn from upper and lower case letters, digits and symbols has about 123 bits of randomness, which is far beyond any practical guessing.
Characters or words?
Random characters pack the most strength into the fewest letters, which suits passwords a password manager types for you. Random words are easier to read aloud and type on a TV remote. For a password you must remember, use the passphrase generator.
Is this page safe to use?
The password is made by your browser's built-in secure random number generator. Nothing you generate is sent to us or stored anywhere, and the generator keeps working if you go offline.