Explain the working of Assembler?

An assembler is the computer program for translating assembly language fundamentally a mnemonic representation of machine language into object code. Also as translating assembly instruction mnemonics into object codes assemblers provide the ability to use symbolic names for memory locations (saving tedious calculations and manually updating addresses when a program is slightly modified) and macro facilities for performing textual substitution usually used to encode common short sequences of instructions to run inline instead of in a subroutine. A cross assembler produces code for one processor but runs on another.