compilers

how do compilers work ?
i mean when you have say c or c++ code or lisp program, how does it turn it into machine code ?
isnt it too complicated and take a lot of machine code ?
or like scheme tail loop, how is it done . its hard to convert just one loop
or like c++ classes theres no clases in machine assmebly
i dont understand

thanks

Trolling aside, I have never read chapters 4 and 5 of SICP. At first, when I saw the Amazon Customer Reviews, I thought that people who said that chapters 4 & 5 are useless in today's world were wrong, but now I see how right they were. PROTIP: There are no lisp machines any more.