A note is a remark in the code that the server doesn't have to interprete.
The remarks are useful to explain the meanings of the variables or the instructions to someone (who can see the code).
The notes are very useful to the author of the code, too if he wants tu use a previuously written program.
Notes in PHP can be of two kinds:
|note in a row only||note in more rows|
$a = 0; //the variable is set to zero
$a = 0;
/* from this point
the code was copied
from the one of Jack */
Pay attention! DON'T insert notes inside an echo instruction!