What is the difference between && and & in php_PHP Tutorial

The first one: && is a logical operator, which represents "and", which is also commonly known as AND. Common ones include the following:

!$a Not TRUE if $a is not TRUE.

$a && $b And (logical AND) TRUE if both $a and $b are TRUE.

$a || $b Or (logical OR) TRUE if either $a or $b is TRUE.
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The second one: & is a bitwise operator, $c = $a & $b, which will set the bits in the binary bits of $a and $b that are both 1 to 1.
For example, 5&3 =>101 & 11 This is binary