A proper noun or proper name is a noun representing unique entities (such as London,Jupiter,John Hunter, orToyota), as distinguished from a 'common noun which describe a class of entities (such as city, planet, person or car). Proper nouns are not normally preceded by an article or other limiting modifier (such as any or some), and are used to denote a particular person, place, or object without regard to any descriptive meaning the word or phrase may have (for example, a town called "Newtown" may be, but does not necessarily have to be, a new [recently built] town).

Capitalization

In English and most other languages that use the Latin alphabet, proper nouns are usually capitalized. Languages differ in whether most elements of multiword proper nouns are capitalized (e.g., American English House of Representatives) or only the initial element (e.g., Slovenian Državni zbor 'National Assembly'). In German, nouns of all types are capitalized. In past centuries, orthographic practices in English, including noun capitalization, varied widely, with less standardization than today. Documents from the 18th century show some writers capitalizing all nouns and others capitalizing certain nouns based on varying ideas of their importance in the discussion. For example, the end (but not the beginning) of the Declaration of Independence (1776) and all of the Constitution (1787) show nearly all nouns capitalized, the Bill of Rights (1789) capitalizes a few common nouns but not most of them, and the Thirteenth Constitutional Amendment (1865) only capitalizes proper nouns. Today English orthography has been standardized to the point that capitalizing common nouns is considered formally incorrect outside of sentence-initial or title case contexts. Although informal writing often dismisses formal orthographic standards (by mutual consent of the communicators), an epistemological stance of orthographic "right and wrong" governs formal writing.

Today the meaning of proper noun capitalization is uniqueness within an implicit context, that is, it provides a name to an instance of a general type when the instance is unique within an implicit context. Most often the implicit context is "the whole world" or "the universe"; thus London, Jupiter, John Hunter, and Toyota are effortlessly understood as being cosmically unique; they derive their proper-noun status (and thus their capitalization) from that fact, and those properties are unequivocal (no one could argue with them). But in instances where a context shift is possible, and the context shift causes a shift from uniqueness to nonuniqueness, the capitalization or lowercasing decision may become a matter of perspective, as discussed below (see especially the examples under "Specific designators"). Sometimes the same word can function as both a common noun and a proper noun, depending on context. Two variants of this principle can be distinguished, although the distinction is blurred by real-world use of the labels to refer to instances of both types. They have no universally agreed names (that is, no standardized metalanguage), but the names "capitonym" and "specific designator" have some currency.

Specific designators

There are many words that are generally common nouns but that can easily "serve temporary proper noun duty" (or "contextual proper noun duty"). Some examples are agency, avenue, boulevard, box, building, bureau, case, chapter, city, class, college, day, edition, floor, grade, group, hospital, level, office, page, paragraph, part, phase, road, school, stage, step, street, type, university, week. The temporary proper noun duty occurs when the common noun is paired with a number or other word to create a name for a specific instance of an abstraction (that is, a specific case of a general type). It is then referred to as a "specific designator". For example:

• Mary lives on the third floor of the main building. (common noun senses throughout)
• Mary lives on Floor 3 of the Main Building. (same information content but recast cognitively as proper names. There is no etic difference except the cognitive one of the specificity that the capitalization imbues. It establishes an implicit sense that "within our commonly understood context [the building complex that we are standing in], the main building being referenced is the only main building. It is a unique object [as far as our context is concerned].)
• My bookmark takes me to the main page of the English Wikipedia.
• What is the proper name of that page?
• It is the Main Page.
• Sanjay lives on the beach road. [the road that runs along the beach]
• Sanjay lives on Beach Road. [the specific road that is named with the capitalized proper name "Beach Road". It is a unique instance of a road in the world, although its proper name is unique only within our province. Our neighboring province also has a road named Beach Road.]
• In 1947, the U.S. established the Central Intelligence Agency.
• In 1947, the U.S. established a central intelligence agency to coordinate its various foreign intelligence efforts. It was named the Central Intelligence Agency.
• India has a ministry of home affairs. It is called the Ministry of Home Affairs. (Within the context of India, it is the only ministry of home affairs, so you can name it by capitalizing the common noun. Within the context of planet Earth, it is a unique organization, but capitalizing the common noun is not a viable way to arrive at a unique proper name for it, because other countries also may use that same name for their unique organization. Another way to say the same idea is that within India's namespace, the naming convention provides sufficient uniqueness of the identifier, but with
  

In the field of linguistics, a sentence is an expression in natural language, and often defined to indicate a grammatical unit consisting of one or more words that generally bear minimal syntactic relation to the words that precede or follow it. A sentence can include words grouped meaningfully to express a statement, question, exclamation, request or command.

As with all language expressions, sentences may contain both function and content words, and contain properties distinct to natural language, such as characteristic intonation and timing patterns.

Sentences are generally characterized in most languages by the presence of a finite verb, e.g. "The quick brown fox jumps over the lazy dog".

Components of a sentence

Clauses

A clause consists of a subjectand apredicate. The subject is typically anoun phrase, though other kinds of phrases (such as gerund phrases) work as well, and some languages allow subjects to be omitted. The predicate is a finite verb phrase: a finite verb together with zero or more objects, zero or more complements, and zero or more adverbials.

There are two types of clauses: independent and subordinate (dependent). An independent clause demonstrates a complete thought; it is a complete sentence: for example, "I am sad." A subordinate clause is not a complete sentence: for example, "because I had to move."

See also copula for the consequences of the verb to be on the theory of sentence structure.

Complete sentences

A simple complete sentence consists of a single clause (subject and predicate). Other complete sentences consist of two or more clauses (see below).

Classification

By structure

One traditional scheme for classifying English sentences is by the number and types of finiteclauses:

• A simple sentenceconsists of a singleindependent clause with no dependent clauses.
• A compound sentenceconsists of multiple independent clauses with no dependent clauses. These clauses are joined together usingconjunctions, punctuation, or both.
• A complex sentenceconsists of at least one independent clause and one dependent clause.
• A complex-compound sentence(or compound-complex sentence) consists of multiple independent clauses, at least one of which has at least one dependent clause.

By purpose

Sentences can also be classified based on their purpose:

• A "declarative sentence" or "declaration", the most common type, commonly makes a statement: "I am going home."
• An "interrogative sentence" or "question" is commonly used to request information — "When are you going to work?" — but sometimes not; "see" rhetorical question.
• An "exclamative sentence" or "exclamation" is generally a more emphatic form of statement expressing emotion: "What a wonderful day this is!"
• An "imperative sentence" or "command" tells someone to do something: "Go to work at 7:30 in the morning."

Major and minor sentences

A major sentence is a regular sentence; it has a subject and a predicate. For example: I have a ball. In this sentence one can change the persons: We have a ball. However, a minor sentence is an irregular type of sentence. It does not contain a finite verb. For example, "Mary!" "Yes." "Coffee." etc. Other examples of minor sentences are headings (e.g. the heading of this entry), stereotyped expressions (Hello!), emotional expressions (Wow!), proverbs, etc. This can also include nominal sentences like The more, the merrier. These do not contain verbs in order to intensify the meaning around the nouns and are normally found in poetry and catchphrases.

Sentences that comprise a single word are called word sentences, and the words themselves sentence words.