"1. There; There is (There are, was, were, has been, have been, had been, will be, would be, etc.) used to show that something (or someone) exists or happens; or In, at, to, into, or toward that place, position, stage, moment, or point:

There is a boy there.
There is a girl over there.
Stop there, where there is no grass.

2. Interjection - Used to express feelings such as relief, satisfaction, sympathy, or anger: 

There, now I can have some peace!
There, there! (Exclamation.)

Also note the following.

3. Contraction of there is = there's (Spoken English).

There's a couple of good reasons.

4. Negating the conjunction (and); Closest Subject Rule - The Subject closest to the verb is Singular.

There is a grasshopper and an ant.

5. Singular or Plural Subject.

There seems to be a bottle in the bag.
There seem to be bottles in the bag."

There vs. Have. [vs. = Vs. = Versus.]

There = Exists or Happens.

Have = To be in possession of. (Be in possession of.)