Comments are notes about the code, they explain the function performed by a specific code.
Comments are extremely important for you and for other people who will use your code. It is a good idea to get used to comment your code as soon as possible. When you will be working on someone else's code, or even your own code after a long time, comments will save your life.
Browsers and servers will ignore comments. In PHP you can use double shash (//) or hash mark (#) syntax for single line comments, slash asterisk (/* … */) syntax for multiline comments.
<span style="color: #ff0000;"><?php </span><br /> <span style="color: #ff00ff;">//this is a single line comment (C++ style)<br /><br /> #this is another way to write a single line comment (Unix shell style)<br /><br /> /*<br /> THIS<br /> IS<br /> A<br /> MULTILINE<br /> COMMENT (C style)<br /> */</span><br /><span style="color: #ff0000;">?></span>
Click here to read about how to output data in PHP.