Memory is main part but we need to know what amount of data do i have or stored. And to understand we use units for measuring Memory.
The smallest unit is bit. Bit means either 0 or 1 in other words passed signal or not.
When we combine and form 4 digit number of bits is called Nibble.
When 8 digit number of bits or we can call 2 Nibbles is Byte.
0 / 1 = 1 bit
4 bits = 1 Nibble
8 bits = 2 Nibbles = 1 Byte
1024 Bytes = 1 Kilobyte (KB)
1024 Kilobytes = 1 Megabyte (MB)
1024 Megabytes = 1 Gigabyte (GB)
1024 Gigabytes = 1 Terrabyte (TB)
1024 Terrabytes = 1 Petabyte (PB)
1024 Petabytes = 1 Exabyte (EB)
1024 Exabytes = 1 Zettabyte (ZB)
1024 Zeetabytes = 1 Yottabyte (YB)
1024 Yottabytes = 1 Brontobyte
1024 Brontobytes = 1 Geopbyte
And lots more in picture below: