What are API calls used for?
"API calls" have no specific question; the term APIsimply means application programming interface, and to call an API simply means to invoke a function (or subroutine) from a computer program.Each API call is different in how it is called (e.g. does it require any parameters, and of so, which), when (e.g. can it be called at any time and under all circumstances), what it does and what it returns to the caller.API functions serving closely related purposes are often grouped together into an API.Take this hypothetical example: One API provides services for rounding numbers: one function of this API rounds numbers to the nearest whole number, another function that belongs to the same API rounds numbers to the nearest hundredth.The purpose of API is unlimited. Examples of API include API to allocate, manage and return memory from a heap, API to create, manage and delete files and folders on a hard disk, API to get and set the current time, API to draw lines and other geometric shapes, etc, etc.