Did you ever read some code and would not understand what it means? Because programs can be very complicated and abstract, supplementary explanations in the form of code comments are very useful.

Even if you think a piece of code does not need an explanation, you should consider adding a comment to it, in case someone else looks at your code (or even you forgot after a while what you meant to write).

A comment is a line of text in the program code, which is ignored by the compiler, and thus may contain any text. In Arduino you can create two types of comments:

These comments are useful to annotate a specific line of code with a short description. They begin with a //. Alternatively you can add a comment to the end of a program statement:

// I am a comment
int led = 13;  // The value 13 is assigned to the variable led.


Additionally these comments are useful, if you want to test a change of your code, without deleting the statements: Just comment the line, and the compiler will ignore the command!

These comments are often times written on top of a program or function. They begin with /* and end with */. All text between these two expressions will be ignored by the compiler. This is also useful to 'disable' a whole block of code during development.

/*
*
* I am a multi-line comment.
* I can describe which purpose a program or function has, and who has written it.
*
* by the way:
* <- these stars are created automatically, but not required for the comment..
*
*/