1. <application, algorithm> To arrange a collection of items in some specified order. The items - records in a file or data structures in memory - consist of one or more fields or members. One of these fields is designated as the "sort key" which means the records will be ordered according to the value of that field. Sometimes a sequence of key fields is specified such that if all earlier keys are equal then the later keys will be compared. Within each field some ordering is imposed, e.g. ascending or descending numerical, lexical ordering, or date.
Sorting is the subject of a great deal of study since it is a common operation which can consume a lot of computer time. There are many well-known sorting algorithms with different time and space behaviour and programming complexity.
Unix manual page: sort(1).