What is idempotency?

Idempotency is a property of an operation where performing the same operation multiple times yields the same result as performing it once.

In the context of web development and APIs, it means that a repeated request with the same parameters will not change the system's state further after the first request.

Example: The HTTP method GET is idempotent because requesting a resource does not change its state. PUT is also idempotent because updating a resource with the same data multiple times will not change the result.

In Node.js, idempotency is important for ensuring the reliability and predictability of APIs, especially when dealing with repeated requests due to network failures or timeouts.