What is "fetch"

The API fetch provides a generic definition of objects from Request and Response (and other entities involved with network requests). This will allow them to be used wherever they are needed in the future, whether for Service Workers, Cache API and other similar Apis that handle or modify requests and replies or any type of use case that may require you to manage your own Answer programmatically.

Source: https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API