Every API has a rulebook. Does anyone check it?
An API is how apps talk to the shop: look at products, place orders. Its rulebook (an OpenAPI spec) lists every door and what you may do at each one.
Without API protectionEvery request walks straight in. If the shop's server answers, it happens.
With Fastly API SecurityA guard at the entrance holds the rulebook. Anything not on it is turned away before it reaches the shop.
Pick a request on the left. It's sent through both at the same time.