A collation sequence determines the sorting order of any given character set. For example, in English, the order of the alphabet is most commonly used to order a list of English words. That is, words beginning with the letter c appear before words beginning with the letter d, which appear before words beginning with the letter e and so on.

A collation sequence is associated with each database when the database is created. This sequence determines in what order sorted data is returned to users and applications, what is returned when queries use pattern matching and, in some instances, how data is stored internally.