1.They’re escape sequences. n is a newline and r is a carriage
return. In Windows most text editors have a newline as rn and on
unix it’s n. 2.r is the carriage return n is the newline These
are available in many other languages aside from PHP. 3.They’re
“carriage return” and “line feed” respectively. Typically on
Windows, you need both together to represent a line terminator:
“rn” whereas on most (all?) Unix systems, “n” is enough.