This group contains instructions for bitwise logical operations which you, being a developer, already know. These are NOT, OR, XOR, and AND operations. However, while high-level languages do make a difference between bitwise and logical operators (for example, bitwise AND (&) and logical AND (&&) in C), they are all the same on the Assembly level and are quite commonly used in conjunction with the EFlags register (or RFlags on 64-bit systems).

For example, consider the following simple snippet in C that checks for a specific bit being set and conditionally executes certain code:

if(my_var & 0x20)
{
   // do something if true
}
else
{
  // do something else otherwise
}

It may be implemented in Assembly like this:

and dword [my_var], 0x20  ; Check for sixth bit of 'my_var'. 
                          ; This operation sets ZF if the result 
                          ; is zero (if the bit is not set).
jnz do_this_if_true       ; Go to this label if the bit is set
jmp do_this_if_false      ; Go to this label otherwise

One of the many other applications of these instructions is the finite field arithmetic, where XOR stands for addition and AND stands for multiplication.