Best practices for designing a REST API: https://stackoverflow.blog/2020/03/02/best-practices-for-rest-api-design/

• Use nouns instead of verbs in endpoint paths
• The action should be indicated by the HTTP request method that we’re making. The most common methods include GET, POST, PUT, and DELETE.
• GET retrieves resources. POST submits new data to the server. PUT updates existing data. DELETE removes data. The verbs map to the CRUD operations.
• Name collections with plural nouns -> articles/, not article/
• Nesting resources for hierarchical objects
• Allow filtering, sorting, and pagination
• Cache data to improve performance

• 400 Bad Request – This means that client-side input fails validation.
• 401 Unauthorized – This means the user isn’t not authorized to access a resource. It usually returns when the user isn’t authenticated.
• 403 Forbidden – This means the user is authenticated, but it’s not allowed to access a resource.
• 404 Not Found – This indicates that a resource is not found.
• 500 Internal server error – This is a generic server error. It probably shouldn’t be thrown explicitly.
• 502 Bad Gateway – This indicates an invalid response from an upstream server.
• 503 Service Unavailable – This indicates that something unexpected happened on server side (It can be anything like server overload, some parts of the system failed, etc.).

If try to submit the payload with the email value that already exists in users, we’ll get a 400 response status code with a 'User already exists' message to let users know that the user already exists. With that information, the user can correct the action by changing the email to something that doesn’t exist.

• Links: https://stackoverflow.com/questions/28459418/use-of-put-vs-patch-methods-in-rest-api-real-life-scenarios