Key takeaway

Passwords and passphrases authenticate an account.

PINs and biometrics usually unlock a trusted device or protected credential. Passkeys authenticate using cryptography and are currently the strongest, phishing-resistant option where supported.

Method

What it is

Typical use

Security posture

Password

A secret string of characters typed by the user.

Websites, apps and legacy systems.

Good only if unique, strong and protected by Multi Factor Authentication (MFA).

Passphrase

A longer password made from multiple words.

Account sign-in where passkeys are unavailable.

Stronger than short passwords, but still phishable.

Passkey

A device-held cryptographic credential, unlocked by biometrics or local PIN.

Microsoft 365, Google, Apple and modern services.

Best option: phishing-resistant and not reusable.

PIN

A short numeric or alphanumeric code used locally.

Windows Hello, mobile devices and smart cards.

Strong when tied to a device and hardware security.

Biometric

A physical trait used to verify the person at the device.

Fingerprint, face recognition and iris recognition.

Convenient and strong locally, but should be backed by a PIN or recovery method.

Something you know: A password, passphrase, or a memorized PIN.

Something you have: A smartphone, a hardware security token, or a USB key.

Something you are: A biometric check like a fingerprint, facial recognition, or an iris

Passwords

Familiar and widely supported, but can be guessed, reused, stolen or captured by phishing. Store unique passwords in a password manager.

Passphrases

Longer sequences of random, unrelated words. Easier to remember and harder to crack, but still need MFA and must not be reused.

Passkeys

Passwordless credentials based on public-key cryptography. The private key stays on the device and sign-in is approved locally.

PINs

Usually local to a device. A Windows Hello PIN unlocks protected credentials rather than being sent to the service.

Biometrics

Use a body characteristic such as fingerprint, face or iris. They verify the person to the device and usually unlock a device-held credential.

Important distinction

Biometrics are convenient, but they generally complement passkeys, PINs or MFA rather than replacing account security on their own.

1. Passkey

2. Passphrase + MFA

3. Strong password + MFA

4. PIN or biometric

Use wherever supported

Use when passkeys are unavailable

Use for legacy systems

Use to unlock trusted devices

Practical Rules

Use passkeys as the best option.

Otherwise use a unique passphrase or strong password with MFA. 

Treat PINs and biometrics as local device-unlock methods, not reusable account passwords.