Philosophy

• Category of being
  Category of being
  In metaphysics , the different kinds or ways of being are called categories of being or simply categories. To investigate the categories of being is to determine the most fundamental and the broadest classes of entities...
  
  
• Categories (Aristotle)
  Categories (Aristotle)
  The Categories is a text from Aristotle's Organon that enumerates all the possible kinds of thing that can be the subject or the predicate of a proposition...
  
  
• Category (Kant)
  Category (Kant)
  In Kant's philosophy, a category is a pure concept of the understanding. A Kantian category is a characteristic of the appearance of any object in general, before it has been experienced...
  
  
• Categories (Peirce)
  Categories (Peirce)
  On May 14, 1867, the 27-year-old Charles Sanders Peirce, who eventually founded Pragmatism, presented a paper entitled "On a New List of Categories" to the American Academy of Arts and Sciences. Among other things, this paper outlined a theory of predication involving three universal categories...
  
  
• Category (Vaisheshika)
• Stoic Categories

Mathematics

• Category (mathematics)
  Category (mathematics)
  In mathematics, a category is an algebraic structure that comprises "objects" that are linked by "arrows". A category has two basic properties: the ability to compose the arrows associatively and the existence of an identity arrow for each object. A simple example is the category of sets, whose...
  
  
• Abelian category
  Abelian category
  In mathematics, an abelian category is a category in which morphisms and objects can be added and in which kernels and cokernels exist and have desirable properties. The motivating prototype example of an abelian category is the category of abelian groups, Ab. The theory originated in a tentative...
  
  
• Category of abelian groups
  Category of abelian groups
  In mathematics, the category Ab has the abelian groups as objects and group homomorphisms as morphisms. This is the prototype of an abelian category....
  
  
• Category of sets
  Category of sets
  In the mathematical field of category theory, the category of sets, denoted as Set, is the category whose objects are sets. The arrows or morphisms between sets A and B are all functions from A to B...
  
  
• Category (topology) in the context of Baire space
  Baire space
  In mathematics, a Baire space is a topological space which, intuitively speaking, is very large and has "enough" points for certain limit processes. It is named in honor of René-Louis Baire who introduced the concept.- Motivation :...
  
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• Category theory
  Category theory
  Category theory is an area of study in mathematics that examines in an abstract way the properties of particular mathematical concepts, by formalising them as collections of objects and arrows , where these collections satisfy certain basic conditions...
  
  
• Equivalence of categories
  Equivalence of categories
  In category theory, an abstract branch of mathematics, an equivalence of categories is a relation between two categories that establishes that these categories are "essentially the same". There are numerous examples of categorical equivalences from many areas of mathematics...
  
  
• Lyusternik–Schnirelmann category, sometimes called LS-category or simply category
• Monoidal category
  Monoidal category
  In mathematics, a monoidal category is a category C equipped with a bifunctorwhich is associative, up to a natural isomorphism, and an object I which is both a left and right identity for ⊗, again up to a natural isomorphism...
  
  
• Preadditive category
  Preadditive category
  In mathematics, specifically in category theory, a preadditive category is a category that is enriched over the monoidal category of abelian groups...
  
  

Computer programming

• Categories, a programming concept in Objective-C
  Objective-C
  Objective-C is a reflective, object-oriented programming language that adds Smalltalk-style messaging to the C programming language.Today, it is used primarily on Apple's Mac OS X and iOS: two environments derived from the OpenStep standard, though not compliant with it...
  
  

Network cabling

• Networking Cable: CAT (1
  Category 1 cable
  Category 1 cable a.k.a. voice-grade copper is a misnomer, probably adopted by those who assumed that TIA set up "Categories" for all types of cables originally defined by Anixter International, the distributor, under the grades called "Levels." Cat 1 cable is used in earlier times...
  
  , 2
  Category 2 cable
  Category 2 cable, or simply Cat 2, is a misnomer, probably adopted by those who assumed that the Telecommunications Industry Association set up "Categories" for all types of cables originally defined by Anixter, the distributor, under the grades called Levels. TIA-568 only recognized cables of...
  
  , 3
  Category 3 cable
  Category 3 cable, commonly known as Cat 3 or station wire, is an unshielded twisted pair cable designed to reliably carry data up to 10 Mbit/s, with a possible bandwidth of 16 MHz...
  
  , 4
  Category 4 cable
  Category 4 is a description of a cable that consists of four unshielded twisted-pair wires with a data rate of 16 Mbit/s and performance of up to 20 MHz. It was used in token ring networks, 10BASE-T, 100BASE-T4, and is no longer common or used in new installations. It is used in telephone...
  
  , 5
  Category 5 cable
  Category 5 cable is a twisted pair cable for carrying signals. This type of cable is used in structured cabling for computer networks such as Ethernet. It is also used to carry other signals such as telephony and video. The cable is commonly connected using punch down blocks and modular connectors...
  
  , 5e, 6
  Category 6 cable
  Category 6 cable, commonly referred to as Cat 6, is a cable standard for Gigabit Ethernet and other network physical layers that is backward compatible with the Category 5/5e and Category 3 cable standards. Compared with Cat 5 and Cat 5e, Cat 6 features more stringent specifications for crosstalk...
  
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Other

• Pregnancy category
  Pregnancy category
  The pregnancy category of a pharmaceutical agent is an assessment of the risk of fetal injury due to the pharmaceutical, if it is used as directed by the mother during pregnancy. It does not include any risks conferred by pharmaceutical agents or their metabolites that are present in breast...
  
  
• Prison security categories in the United Kingdom
  Prison security categories in the United Kingdom
  There are four prisoner security categories in the United Kingdom used to classify every adult prisoner for the purposes of assigning them to a prison. The categories are based upon the severity of the crime and the risk posed should the person escape....
  
  
• List of boxing weight classes
• List of software categories
• Saffir–Simpson Hurricane Scale - common categorization of hurricane intensities
• Lexical category
  Lexical category
  In grammar, a part of speech is a linguistic category of words , which is generally defined by the syntactic or morphological behaviour of the lexical item in question. Common linguistic categories include noun and verb, among others...
  
  
• Categories of New Testament manuscripts
  Categories of New Testament manuscripts
  New Testament manuscripts in Greek are categorized into five groups, according to a scheme introduced in 1981 by Kurt and Barbara Aland in Der Text des Neuen Testaments. The categories are based on how each manuscript relates to the various text-types. Generally speaking, earlier Alexandrian...
  
  

See also

• Categorical (disambiguation)
• Categorization
  Categorization
  Categorization is the process in which ideas and objects are recognized, differentiated and understood. Categorization implies that objects are grouped into categories, usually for some specific purpose. Ideally, a category illuminates a relationship between the subjects and objects of knowledge...
  
  
• Category 1 (disambiguation)
• Category 2 (disambiguation)
• Category 3 (disambiguation)
• Category 4 (disambiguation)
• Category 5 (disambiguation)
• Category 6 (disambiguation)
• Category 7: The End of the World
  Category 7: The End of the World
  Category 7: The End of the World is a 2005 four-hour television film miniseries that was broadcast in the United States on CBS in two parts, the first part aired on November 6 and the second on November 13. A sequel to the 2004 miniseries Category 6: Day of Destruction, this film starts directly...
  
  
• Category A (disambiguation)
• Category B (disambiguation)
• Category C (disambiguation)