Types of partitions, and there type of usage

Majorly there are 2 types of partitions i.e. Data and swap partition.

Data - There are like boot partitions which hold data like files/folders. This partition may contain files which start and run linux OS.

Swap - This partition is used by linux only in case the available RAM is full and instead this space is used to store the RAM data to prevent system failure. This is one the key & popular feature of Linux. Hence, to mount this special entry with option SW is mentioned inside /etc/fstab to make Linux OS know that this partition needs to be treated as SWAP.