We use “there + be” to talk about the existence of something. “There + be” can be used in all verb tenses, but is conjugated in order to distinguish between singular or plural and countable or uncountable.
“There is” is used with countable nouns in singular and uncountable nouns. The short form is “there’s”.
“There are” can only be used with countable nouns in plural. There is no short form.
Note: There are some verb tenses in which we do not conjugate “there + be” to indicate plural or singular, countable or uncountable. These verb tenses include the future (“will”), the past perfect and when used with modal verbs. For more information, see the lessons relating to these various verb tenses.
There v. It
We use “there” when we speak of something for the first time, to indicate that it exists. On the other hand, we use “it” to speak of something specific or something already mentioned.