1. Information, in any form, on which computer programs operate. The distinction between program (instructions) and data is a fundamental one in computing (see von Neumann machine). It is in this fundamental sense that the word is used in terms such as data, data break, data bus, data cartridge, data communications, data compression, data name, data protection, data subject, and data type.

2. In a more limited sense, data is distinguished from other contrasting forms of information on which computers operate, such as text, graphics, speech, and image. The distinguishing characteristic is that it is organized in a structured, repetitive, and often compressed way. Typically the structure takes the form of sets of fields, where the field names are omitted (this omission being a main means of achieving compression). The ‘meaning’ of such data is not apparent to anyone who does not know what each field signifies (for example, only a very limited meaning can be attached to ‘1234’ unless you know that it occupies the ‘employee number’ field). That characteristic gives rise to the popular fallacy that ‘data is meaningless’.

Terms such as database, data dictionary, data hierarchy, data independence, data model, data preparation, and data processing normally carry this second sense—though not invariably; the context should determine which sense is intended.

3. See statistical methods, statistics.