A swapfile is a special file created on your computer’s disk, which will hold some of the memory contents. For example, when the main memory is starting to get full, the computer may write some of its memory to the swap space on the disk, which, albeit much slower than memory, will work as extra memory in the machine.
This is a companion discussion topic for the original entry at https://linuxconfig.org/how-to-create-swapfiles-in-ubuntu-and-mint