Bitmask (example from The Audio Programming Book pg 22)

[Fauveboy]

I think I'm getting confused by the use of Hexadecimal values...I do not understand what bitmasking is with this example? I can't see whats happening as a result of the code to demonstrate this feature. Can someone explain what Bitmasking is and how this following code represents that? is it ( going from the right of hexadecimal ) values comparing 0 & 1, then 0 & 1, then F & 1 (is F & 1 = the "1" in 0x0100, which is the result that prints out)? ect....?

  short mask = 0xFF00, value, masked;
    value = 0x0111;
    masked = mask & value;
    
    printf("bitmask: %#x \n\n", masked);

[Fauveboy]

...a single hexadecimal value, by isolating one such as 0xF(F, the "F" here)00, is represented by four bits?...is that global for all computers? how would to book know to demonstrate the 0xFF00 as 1111 1111 0000 0000 ? that might vary on a different machine? and also why is the 0x not represented in the binery ?

[john.c]

Hex is just the base-16 number system, so it's the same for all machines and each hex digit is shorthand for 4 bits.