Indefinite pronouns refer to people, things, or quantities without naming them directly. They can stand alone as the subject or object of a clause, and many of them control singular agreement even when their meaning feels general or plural. Because they often replace longer noun phrases, they are closely linked to Subject Pronouns, Object Pronouns, and Possessive Pronouns.

Words for people form a small system of indefinite reference. Someone and somebody mean an unspecified person, anyone and anybody are common in questions and conditions, no one and nobody are negative forms, and everyone and everybody mean all people in a group. Singular they often replaces he or she after these pronouns when the gender is unknown or irrelevant.

Idea	Example
Someone and somebody refer to one unspecified person.	Someone called after lunch.
Anyone and anybody are common in questions and conditional clauses.	Does anybody need help?
No one and nobody make the meaning negative.	Nobody answered the door.
Everyone and everybody refer to all people in a group.	Everyone is ready now.
Singular they can follow an indefinite person word.	Someone forgot their bag.

Indefinite pronouns for things use the same polarity patterns as the people words. Something is used in affirmative statements, anything is common in questions and negative contexts, nothing means no thing, and everything means all things in a set. These forms are not used with a following noun, and they refer to the whole idea of a thing rather than a specific item.

Idea	Example
Something refers to an unspecified thing.	Something moved in the kitchen.
Anything is common in questions and negative clauses.	Did you hear anything strange?
Nothing carries a negative meaning.	Nothing seems broken.
Everything refers to all things in a set.	Everything looks clean now.
Thing words stand alone and do not take a following noun.	Something happened outside.

Several indefinite pronouns are singular in grammar even when they mean many people or many things. Each, either, neither, one, another, nobody, no one, everyone, somebody, and anyone usually take singular verbs, while singular pronouns and possessives often follow the same pattern. In careful English, none and some may take singular or plural agreement depending on whether the writer treats them as one whole or as separate parts.

Idea	Example
Each takes a singular verb.	Each of the students is present.
Either and neither usually take singular agreement.	Neither answer is correct.
One and another refer to single items.	One of the books is missing.
None may take singular or plural agreement.	None of the water is left.
Some may take singular or plural agreement in practice.	Some of the cakes are gone.

All, some, none, most, both, few, and many express amount rather than identity. The verb agreement depends on the noun or idea that follows, so plural count nouns usually take plural verbs and singular mass nouns usually take singular verbs. Both, few, and many normally point to plural reference, while all, some, none, and most change with the noun or context.

Idea	Example
All can match singular or plural reference.	All of the milk is cold.
Most can match singular or plural reference.	Most of the chairs are empty.
Both normally refers to two plural items.	Both of the doors are open.
Few and many normally take plural reference.	Many of the guests are late.
Some and none depend on the noun or context.	Some of the advice is useful.

Each other and one another show a mutual relationship between two or more people or things. They usually function after a plural subject and do not replace a subject pronoun by themselves. These forms are useful when the action goes in both directions, and they are often followed by a possessive form or an object-like complement in the same clause.

Idea	Example
Each other is common for two-way actions.	The friends helped each other.
One another is also used for mutual reference.	The team members support one another.
These forms follow a plural subject.	The children looked at each other.
They express a shared action or feeling.	The neighbors trust one another.
They do not name the participants directly.	The speakers thanked each other.

Indefinite pronouns let English refer to people, things, and amounts without naming a specific noun. Their grammar is often singular even when the meaning is general, and agreement depends on whether the word is treated as a unit or as part of a larger noun phrase. Their forms, polarity patterns, and reciprocal uses connect naturally with Demonstrative Pronouns, Interrogative Pronouns, Relative Pronouns, and Reflexive Pronouns.