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Sorting refers to various ways of arranging or ordering things.

Sorting information or data

One important kind of sorting is arranging items of information in sequence according to some pre-defined ordering, e.g. when one sorts the books in a library alphabetically by title, subject or author. The problem of how to change the order of lists according to given criteria is simply called sorting in computer science. It is one of extensively researched subjects in it; see sort algorithm.

The main purpose of sorting information is to optimise its usefulness for specific tasks. In general, there are two ways of sorting information: by category e.g. a shopping catalogue where items are grouped together under headings such as 'home', 'sport & leisure', 'women's clothes' etc. and in a hierarchy according to some property e.g. from cheapest to most expensive. Richard Saul Wurman, in his book Information Anxiety, proposes Alphabetical, by Location and by Time as being the most common sorting methods (these are actually special cases of category and hierarchy). Together these give the acronym LATCH (Location, Alphabetical, Time, Category, Hierarchy) and can be used to describe just about every type of ordered information.

Often information is sorted using different methods at different levels of abstraction: e.g. the UK telephone directories which are sorted by location, by category (business or residential) and then alphabetically. New media still subscribe to these basic sorting methods: e.g. a Google search returns a list of web pages in a hierarchical list based on its own scoring system for how closely they match the search criteria (from closest match downwards).

Physical sorting processes

Various sorting tasks are essential in industrial processes. For example, during the extraction of gold from ore, a device called a shaker table uses gravity, vibration, and flow to separate gold from lighter materials in the ore. Sorting is also a naturally occurring process that results in the concentration of ore. Sorting results from the application of some criterion or differential stressor to a mass to separate it into its components based on some variable quality. Materials that are different, but only slightly so, such as the isotopes of uranium, are very difficult to separate.