It (pronoun)

In Modern English, it is a singular, neuter, third-person pronoun.

Morphology

In Modern English, it has only three shapes representing five word forms:it: the nominative and accusative forms. its: the dependent and independent genitive formsitself: the reflexive and intensive form
Historically, though, the morphology is more complex.

History

Old English

Old English had a single third-person pronoun – from the Proto-Germanic demonstrative base *khi-, from PIE *ko- "this" – which had a plural and three genders in the singular. The modern pronoun it developed out of the neuter, singular. The older pronoun had the following forms:
This neuter pronoun, like the masculine and feminine ones, was used for both people and objects. Common nouns in Anglo-Saxon had grammatical genders, which were not necessarily the same as the gender of the person referred to. For instance, Old-English is neuter, as are both and, literally "male-child" and "female-child".
The word,, is also neuter. was grammatically male, but meant "a person", and could, like, be qualified with a gender. meant "female person" and was grammatically masculine, like its last element,, and like . Archbishop Ælfric's Latin vocabulary gives three Anglo-Saxon words for an intersex person,,, and .
Similarly, because is feminine, so are,, and . is neuter, feminine, and both mean "the Angles, the English people". Nouns for inanimate objects and abstract concepts also had genders. Mark Twain parodied this grammatical structure by rendering it literally into modern English:
About half of the world's languages have gender, and there is a continuum between those with more grammatical gender, and those with more natural gender. The concept of natural gender was beginning to develop in Old English, occasionally conflicting with the established grammatical gender. This development was, however, mostly to take place later, in Middle English.

Middle English (1066">Norman conquest of England">1066–1400s)

In the 12th century, it started to separate and appear without an h. Around the same time, one case was lost, and distinct pronouns started to develop, so that by the 15th century, the forms of it were as follows:

Nominative: it
Accusative: it / him
Genitive: his
Reflexive:it self. Also -selfe, -selve'', -silf, -sijlfe'', sometimes without a space.

During the Middle English period, grammatical gender was gradually replaced with natural gender in English.

Modern English (a bit before 1550–present)

Middle English gradually gave way to Modern English in the early 16th century. The hit form continued well into the 16th century but had disappeared before the 17th in formal written English. Genitive its appeared in the later 16th century and had taken over by the middle of the 17th, by which time it had its modern form. "Hit" remains in some dialects in stressed positions only; some dialects also use "it", not "its", as a possessive.

Gender

It is considered to be neuter or impersonal/non-personal in gender. In Old English, it was the neuter nominative and accusative form of hē. But by the 17th century, the old gender system, which marked gender on common nouns and adjectives, as well as pronouns, had disappeared, leaving only pronoun marking. At the same time, a new relative pronoun system was developing that eventually split between personal relative who and impersonal relative which. As a result, some scholars consider it to belong to the impersonal gender, along with relative which and interrogative what.

Syntax

Functions

It can appear as a subject, object, determiner or a predicative complement. The reflexive form also appears as an adjunct. It very seldom appears as a modifier.

Subject: It's there; it being there; its being there; it allows for itself to be there.
Object: I saw it; I pointed her to it; It connects to itself.
Predicative complement: In our attempt to fight evil, we have become it; It took more than ten years it, to fully become itself.
Determiner: I touched its top.
Adjunct: It did it itself.
Modifier: ''They were the it crowd.''

Dummy ''it''

A dummy pronoun is one that appears only for syntactic reasons and has no semantic value. One use of it is as a dummy pronoun as in it's raining or it's clear that you understand.
In Old English, a subject was not required in the way it is today. As the subject requirement developed, there was a need for something to fill it with verbs taking zero arguments. Weather verbs such as rain or thunder were of this type, and, as the following example shows, dummy it often took on this role.

Gif on sæternesdæg geðunrað, þaet tacnað demena and gerefena cwealm
If on saturn's-day thunders, that portends judges' and sheriffs' death
If it thunders on Saturday, that portends the deaths of judges and sheriffs

But these were not the only such verbs. Most of the verbs used without a subject or with the dummy it belong to one of the following semantic groups:

Events or happenings
Seeming or appearance
Sufficiency or lack
Mental processes or states

And examples still remain, such as the expression suffice it to say.
The same use of dummy it exists in cleft constructions, such as it's obvious that you were there.

Dependents

Pronouns rarely take dependents, but it is possible for it to have many of the same kind of dependents as other noun phrases.

Relative clause modifier: That's not the it that I meant; *That's not it that I meant.
Determiner: That's not the it that I meant; *That's not the it.
Adverb phrase external modifier: ''not even itself''

Semantics

It is used to denote an inanimate physical object, abstract concept, situation, action, characteristic, and almost any other concept or being, including, occasionally, humans.
It is usually definite and specific, but it can also have no referent at all. It can be debatable whether a particular use is a dummy it or not.
Samuel Taylor Coleridge proposed using it in a wider sense in all the situations where a gender-neutral pronoun might be desired:
The children's author E. Nesbit consistently wrote in this manner, often of mixed groups of children: "Everyone got its legs kicked or its feet trodden on in the scramble to get out of the carriage." This usage also occurs in District of Columbia police reports.
Some people use it as a gender-neutral pronoun.

Pronunciation

According to the OED, the following pronunciations are used:

Form	IPA	Recording
it	/ɪt/
its	/ɪts/
itself	/ɪtˈsɛlf/ /ᵻtˈsɛlf/

Popular culture

Stephen King's 1986 book It is about a shape shifting, malevolent entity that often manifests as a clown.
In games of tag, the person trying to tag others is known as it.