'Haber' vs. 'Estar'
Both the verbs estar and haber can be used to indicate the presence of a person or thing. However, they are seldom interchangeable.
The difference is that haber, typically in the form of hay in the present tense or había for the past, is used to indicate the mere existence of the person or thing. Estar, on the other hand, is used to indicate the location of the person or thing.
Note, for example, the difference between these two simple sentences:
- No hay presidente. This sentence indicates that the president doesn't exist, perhaps because the office is vacant.
- El presidente no está. This sentence might be used, for example, to indicate that the president isn't present, although he or she exists somewhere.
Sometimes, the difference in meaning between estar and haber can be subtle. Note the difference between these two sentences:
- El juguete está en la silla. (The toy is on the chair.)
- Hay un juguete en la silla. (There is a toy on the chair.)
As a practical matter, there's not a lot of difference in meaning. But grammatically, the verb (está) in the first sentence is used to indicate location, while the verb (hay) in the second sentence indicates mere existence.
As a general rule, estar is used when a specific person or thing is referred to, but a third-person form of haber can be used when the word is used more generically. As a result, a noun preceded by a definite article (the word el, la, los or las, meaning "the"), a demonstrative adjective (a word such as ese oresta, meaning "that" or "this," respectively) or a possessive adjective (such as mi or tu, meaning "my" or "your," respectively) normally would be used with estar.
Here are some more examples:
- No hay ordenador. (There isn't any computer.) El ordenador no está. (The computer isn't here.)
- ¿Había fuegos artificiales? (Were there fireworks?) Esos fuegos artificiales están allí.(Those fireworks are there.)
- ¿Hay tacos de res? (Are there beef tacos available?) Mis tacos no están. (My tacos aren't here.)
With nouns that can't have a location, haber must be used: No había problema. (There was no problem.) Hay riesgo inmediato. (There's an immediate risk.)