Knowing whether to use “there is” or “there are” in a sentence is a function of the noun that comes after each of them. You should use “there is” before a singular noun, and “there are” before a plural noun. Basically, both “there is” and “there are” are deployed to say that something exists or some things exist, as the case may be.
A simple rule of concord requires agreement between verbs and their corresponding nouns for cohesion. “Is” and “are” belong to the same category of verbs, but they are useable with nouns on the premise of number. Is goes with a singular noun while are is compatible with plural nouns
There is vs. There are in sentences
Use “there is” for a singular noun, use “there are” for a plural noun. As we earlier established, the verbs after “there” in these two structures already give a clue to what is likely, or better still, what must come after them. Let us pair them up to have a better grasp of the concept.
There is a big lion in the zoo.
There are many big lions in the zoo (note many as a determiner).
Using “there is” with uncountable nouns
Uncountable or non-count nouns, as the names implied, cannot be counted. They are rather quantified using units of measurement. In describing non-count nouns, use there is.
There is some milk left in the tin.
There is little cereal in the jar.
Asking questions with “there is” or “there are”
Both “there is” and “there are” can be restructured to ask questions. In this case, we transfer the verbs to the beginning of the sentence, as we have in the following:
Is there some water left in the tank?
Are there oranges left on the tray?
Note that “there is” or “there are” can also be employed in providing succinct answers to the questions above. In that case, we have:
Yes, there is or No there isn’t (for question 1)
Yes, there are or No, there aren’t
“There is” or “There are” + A lot of
The expression “a lot of” implies many or much of what is being talked about. It practically dictates what it should be used with: there are.
There are a lot of eCommerce businesses in the world today.
There are a lot of startups without funds.
Using “there is” or “there are” with a list of items
Basically, a list contains more than one item rolled out in succession but separated by commas. The simple rule to follow is to consider the first item on the list. If the first item is in the singular form, use there is.
There is a book, a book, a pencil, and a box of chocolates on my table.
If the first item on the list is in the plural form, especially with determiners such as many and cardinal adjectives, use there are.
There are five books, three pencils, and 2 boxes of chocolates on my table.
NB: While “there is” can be contracted to give “there’s,” it is not intelligible to contract “there are” to “there’re.”