The existential 'there is' construction is used to indicate the existence or presence of something. It introduces a topic or brings something into focus.
'There is' is used for singular nouns or uncountable nouns. In the phrase 'there is,' 'there' serves as an introductory subject. It doesn't have the typical semantic content of a subject but is used to introduce the existence or presence of something.
There is a book on the table.
There are three apples in the basket.
There was a loud noise outside last night.
There were many people at the concert.
The existential 'there' is different from the locative 'there' (indicating place). In the existential construction, 'there' doesn't refer to a specific location but serves as a dummy subject to introduce the real subject. A common mistake is mismatching the verb with the noun in number. For example, 'There is apples' is incorrect; it should be 'There are apples.'In informal speech, especially in questions and negatives, some might use 'there's' (there is) with plural nouns, e.g., 'There's a lot of people here.' While this is accepted in casual contexts, it's considered non-standard in formal writing.