Logging in to a website is so easy: I enter my username and password and can use the site. That's it.
What seems so simple is actually simple if the site is based on a monolithic application. But what if a website is powered by multiple microservices? How do the microservices know that a user is who s/he claims to be, and how can this be handled efficiently? The use of JSON Web Tokens can provide a secure and high-performance solution here.