In Unix-like operating systems, sort is a standard command line program that prints the lines of its input or concatenation of all files listed in its argument list in sorted order. Sorting is done based on one or more sort keys extracted from each line of input. By default, the entire input is taken as sort key. Blank space is the default field separator.
Sort is used in windows systems too
The context says sort is a Unix function, I say you can sort in windows too. That info is something I made up so it should be incorrect. 