If you do any AVR programming in c or c++, you'll very likely need these operations. As often as I've seen them, I still sometimes need to look these up if I haven't used them in a while. So here they are...
Assume that the variable myByte is a 8 bit variable defined as the following in c code:
byte myByte = 0x00;
The above line of code sets all 8 bits (0-7) to 0, turning them all OFF using the hex notation.