what does swap file mean code example

Example: create swap file

#Create a file that will be used for swap:
sudo fallocate -l 1G /swapfile

#If faillocate is not installed or if you get an error message saying fallocate failed: Operation not supported then you can use the following command to create the swap file:
sudo dd if=/dev/zero of=/swapfile bs=1024 count=1048576

#Only the root user should be able to write and read the swap file. To set the correct permissions type:
sudo chmod 600 /swapfile

#Use the mkswap utility to set up the file as Linux swap area:
sudo mkswap /swapfile

#Enable the swap with the following command:
sudo swapon /swapfile

#To make the change permanent open the /etc/fstab file and append the following line:
/etc/fstab
/swapfile swap swap defaults 0 0

#Copy
#To verify that the swap is active, use either the swapon or the free command as shown below:
sudo swapon --show

#NAME      TYPE  SIZE   USED PRIO
#/swapfile file 1024M 507.4M   -1
#sudo free -h
#              total        used        free      shared  buff/cache   available
#Mem:           488M        158M         83M        2.3M        246M        217M
#Swap:          1.0G        506M        517M