The verb be takes on different forms in the present and past.
I
He
She
It
You
They
we
Present
am
is
is
is
are
are
are
Contraction
'm
's
's
's
're
're
're
Past
was
was
was
was
were
were
were
The verb be indicates existence, temporary condition or permanent status.
It is really hot today. Grady's not here right now. Greg and Tim are engineers. Trudy was sick yesterday. Hawaii is in the Pacific Ocean. The base form is be, the past participle is been, and the -ing form is being.
I'll be back tomorrow. He has been a doctor since 1998. She is being nice today.