$a =     9;
$b =     10;
echo $a & $b;

place value   128  64  32  16   8  4   2   1
$a                     0      0    0     0    1  0   0   1   =9
$b                     0      0    0     0    1   0  1   0   =10

result   8  

 only bit they share together is the 8 bit. So 8 gets returned.

  $a =     36;
$b =     103;
echo $a & $b;

place value   128  64  32  16   8    4   2   1
$a                     0      0    1     0    0    1   0   0   =36
$b                     0      1    1     0    0    1   1   1   =103

result  32+4 = 36
the only bits these two share together are the bits 32 and 4 which when added together return 36.

$a =     9;
$b =     10;
echo $a | $b;

place value   128  64  32  16   8  4   2   1
$a                     0      0    0     0    1  0   0   1   =9
$b                     0      0    0     0    1   0  1   0   =10

result 8+2+1 = 11
 3 bits set, in the 8, 2, and 1 column.add those up 8+2+1 and you get 11

$a =     9;
$b =     10;
echo $a ^ $b;

place value   128  64  32  16   8  4   2   1
$a                     0      0    0     0    1  0   0   1   =9
$b                     0      0    0     0    1   0  1   0   =10

result  2+1 = 3
the 2 bit and the 1 bit that they each have set but don't share. Soooo 2+1 = 3