Sign in
Who: everyone. Go to: the Welcome screen → Sign in.
Use email and password, or Google, Microsoft or Apple (Apple on iPhone, iPad and Mac only). If the email address matches, every method opens the same account. In a browser you can also tap Sign in with a passkey (Touch ID, Windows Hello or your phone) once you've added one: see Sign in with a passkey.
Example: Aisha signed up with her work email and a password. Later she taps Continue with Microsoft using the same work email, and lands in the same account.