What are \r and \n meaning in PHP? -

What are they called \ r \ nand what's a tutorial that tells them?

These are respectively "cart return" and "line feed". Generally on Windows, you need both to simultaneously represent line terminator: "\ r \ n" While most (all?) On Unix systems, "\ n" is sufficient.

For more information see the irregularities of different systems.

For more information about Escape sequences in general, and look for other people available in PHP.

Many other languages ​​(like C, C ++, C #, Java, Pearl, Python, Ruby) share the same escape sequences for carriage returns and line feeds - but they all differ (In other words, it is is language specific, but it will also be answered for many languages.)