Grammatical Number, Person and Case

Number, person, and case are grammatical categories that help show relationships between words in a sentence.

Number

English distinguishes primarily between singular and plural.

student / students
book / books
child / children

Number affects nouns, pronouns, determiners, and some verb forms:

This student is ready.
These students are ready.

Some nouns have unusual number patterns:

child → children
mouse → mice
sheep → sheep

Some nouns are normally uncountable:

information, advice, furniture, knowledge

These do not usually form ordinary plurals when used in their standard meanings.

Person

English recognizes three grammatical persons.

First person refers to the speaker:

I, we

Second person refers to the person addressed:

you

Third person refers to someone or something else:

he, she, it, they

Person affects some verb forms:

I work.
You work.
He works.

The verb be shows particularly clear distinctions:

I am
you are
he/she/it is
we/they are

Case

Case indicates the grammatical relationship or function of a noun or pronoun.

Modern English has relatively limited case marking on nouns, but pronouns retain several forms.

Subjective forms:

I, he, she, we, they

Objective forms:

me, him, her, us, them

Possessive forms:

my/mine, his, her/hers, our/ours, their/theirs

Compare:

She called him.
He called her.

The noun itself usually does not change:

Ahmed called Bilal.
Bilal called Ahmed.

Word order therefore plays a major role in identifying grammatical relationships.

Possessive Case

English retains a visible possessive construction:

Ahmed’s car
the teacher’s office
the students’ books

For singular nouns, ‘s is normally used:

the girl’s bag

For regular plural nouns ending in -s, an apostrophe is normally added:

the girls’ bags

Irregular plurals generally take ‘s:

the children’s books
the men’s room

Understanding number, person, and case helps explain why English forms change in different grammatical environments.