What does ORG Assembly Instruction do?

Question

can anyone give me a comprehensive description about ORG directive?
When and why is it used in assembly written applications?

Using Nasm on x86 or AMD64.

Answer 1

      During the assemble time ORG directive resets the MLC (memory location counter) to the address specified in the ORG directive.

Syntax: ORG note: may be a unsigned absolute value or any symbol or symbol + .

example:- to observe this instruction working you need any assemble listing which uses ORG directive.

location
0000A4 00 89 TAB DC 256AL1(*-TAB)
0001A4 00000194 90 ORG TAB+240
000194 F0F1F2F3F4F5F6F7 91 DC C'1234567'

Here in the above the TAB symbol is assigned to MLC address 0A4. in the next instruction ORG sets the MLC to TAB+240 address location which is x'194' (~ x'A4' + 240 in decimal). basically this set up is setup a table with length 256 and from 240 th location to store some character constants so that I can use it for TR instruction.