Understanding the partition system in linux

linux_installing_partition_guide

1. 'dev' refers to device. in my case i have a ssd and a hdd. so while installing linux it will show 
one of them as 'dev/sda' and other as 'dev/sdb'. 'sd' refers to disk and adds an alphabet to it's end to alphabetically organize.

2. under each disk we will have partition of that disk. each partition will append a number to organize them. ex: sda1, sda2, sdb1, sdb2 ...

follow this link on Step 4: Partition Magic https://medium.com/@killyourfm/the-beginners-guide-to-installing-ubuntu-linux-18-04-lts-6c8230036d84

The part which is the main focus of this gist:

Sidebar: Here’s how Linux identifies devices. “dev” simply means “a device that you can read from or write to.” Then we see “sda, sda1, 
sda2,” etc. In Unix “sd” indicates a block device that can carry data. Then it identifies them alphabetically in the order they’re 
discovered. Finally, the number (1, 2, 3) indicates the partitions. So /dev/sda1 simply means the first partition of the first drive.
Partitions? Think of them as slices of a pie. You can use one entire drive without doing anything to it. Or you can divide it into 
partitions — logically but not physically separating them. One of my 2TB drives is divided into 1TB partitions. 
The 2nd partition is just for Steam game installations, so even if I reinstall an operating system, that part of the drive remains 
intact and loses no data. With Linux, partitions are necessary.