Single Line Comments
The single line comment begins with “//” or “#”. When encountered, all text to the right will be ignored by the PHP interpreter.
// This is a comment # This is also a comment echo "Hello World!"; // This is also a comment, beginning where we see "//"
Multi Line Comments
The multi-line comment can be used to comment out large blocks of code. It begins with /* and ends with */
/* This is a multi-line comment. It spans multiple lines. This is still part of the comment. */