A1
hay — there is, there are
How the Spanish impersonal hay works, why it has no plural, and how it differs from estar.
Hay means there is and there are. It is a form of haber, and it never changes.
Hay un problema.
there-is a problem
There’s a problem.
Hay muchas personas.
there-is many people
There are a lot of people.
Han muchas personas.
Hay muchas personas.
Hay has no plural. However many there are, the word does not change — which is one fewer thing to conjugate.
hay against está
Hay introduces something new and unspecified. Está says where something already identified is.
Hay un banco en la esquina.
there-is a bank on the corner
There’s a bank on the corner.
El banco está en la esquina.
the bank is on the corner
The bank’s on the corner.
The article decides it. Hay is followed by un, a number, or nothing at all — never by el, la or a name.
Hay el banco en la esquina.
El banco está en la esquina.
Something definite cannot follow hay. If you can name it, it takes estar.
In other tenses
Había (there was), habrá (there will be), ha habido (there has been). All stay singular.
Había mucha gente.
there-was much people
There were a lot of people.
hay que — one must
Followed by an infinitive it becomes an impersonal obligation, with no subject at all.
Hay que estudiar.
there-is that to-study
You have to study.