The shift operations allow bits to be moved to the left or right in a word. There are three types of shift operations: logical, rotate and arithmetic.
$a & $b - And - Bits that are set in both $a and $b are set.
$a | $b - Or (inclusive or) - Bits that are set in either $a or $b are set.
$a ^ $b - Xor (exclusive or)- Bits that are set in $a or $b but not both are set.
~ $a - Not - Bits that are set in $a are not set, and vice versa.
$a << $b - Shift left - Shift the bits of $a $b steps to the left (each step means "multiply by two")
$a >> $b - Shift right - Shift the bits of $a $b steps to the right (each step means "divide by two")