# What is an API gateway?

* An API gateway is the pathway traffic endpoint to an API. An API can be linked to multiple API gateways; however, one API gateway can use only one API at a time. 
*  In the API gateway, users can define the number of requests daily or monthly or the total amount of requests the API should accept. 
* API gateways can also have tags. 
* Suppose a Validation pipeline is to be applied to data before being updated in entities (during the execution of the API). In that case, the Validation pipeline can be configured in the API gateway in the Entities tab. 
* If a Flow is to be triggered, the Flow can be configured in the API gateway in the Entities tab.

{% embed url="<https://media.langstack.com/documentation/media/images/code/training_manual/chapter_2/ch2whatisanapigateway.png>" %}


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