What is a magic link?

A magic link is a unique, single-use link sent by e-mail or SMS; clicking it authenticates the subject directly. Links usually have a short validity and belong to the passwordless authentication methods.

Security rests entirely on control of the mailbox or phone number, so it inherits the security of that channel.

Go deeper:

• Passwordless authentication (Wikipedia) — magic links, biometrics and FIDO as replacements for the password.