Plus, how to increase its size
What is a swap file or swap file asap
The Windows paging file is a special file that contains data that your RAM cannot hold when it reaches its limits. Your system RAM has a limit. If your system tries to exceed that limit, it may send some of the data to the paging file.
It is not the most efficient way to manage your system memory. However, a swap file is necessary and keeps your system running smoothly.
Here's what a Windows 10 paging file is and how a paging file works.