The verb 'to be' is very important in English. We use 'am', 'is', and 'are' to talk about who someone is, how someone is, or what something is. For example:
I am a student.
She is happy.
They are friends.
Singular Forms of "To Be" (1)
am
are
is
Use 'am' with 'I'.
Use 'are' with 'you'.
Use 'is' with 'he', 'she', 'it', one person (Tom or Kim), or one thing (cat or box).
Singular Subject (1)
'To Be'
Example
I
am
I am a student.
you (singular)
are
You are my friend.
he
is
He is happy.
she
is
She is happy.
it
is
It is a cat.
Tom
is
Tom is a student.
Kim
is
Kim is a teacher.
I am a student.
You are my friend.
He is happy.
She is happy.
It is a cat.
Tom is a student.
Kim is a teacher.
Plural Forms of "To Be" (2+)
are
Use 'are' with you (plural), we, they, or more than one person or thing.