How does authentication work?

Authentication is how the apps you use know that you are who you say you are: through something as simple as a password, or as complex as biometrics.

• Accessing your apps and data on the web relies on identity: only you should be able to see your stuff!
• The most popular authentication method is username and password, but schemes like single-sign-on and magic links are getting more popular
• On the backend, authentication can work through cookies, session tokens, and/or other combinations of esoteric cryptography

Pretty much every app developer has to build authentication if they want people to use what they’re making. Auth0 – which lets developers outsource authentication – just exited for $6.5B (!). So the space is probably worth understanding.