As a programmer, it is good practice to write well-documented code that can be read months later by you or any other developer. It simply makes a developer's life easier who want to make some changes or a few updates on your code.
PHP ignores the commented text during the execution of the script. PHP follows C++ style commenting. You can use the double forward slash to comment a single line. You can also write multiline comments using the /* */ combination that expands over several lines and write a heading or lengthy.
The /* */ code combination is used to write comments that extend over several lines. Helpful is writing a lengthly explanation.