Difference between & and && in PHP

Question

I am confused with & and &&. I have two PHP books. One says that they are same, but the another says they are different. I thought they

Answer 1

 

AND operation: 

& -> will do the bitwise AND operation , it just doing operation based on
      the bit values. 
&&   -> It will do logical AND operation. It is just the check the values is 
       true or false. Based on the boolean value , it will evaluation the 
       expression