Pronouns replace nouns within sentences. For example, if I said "Alex went to the movies and Alex got popcorn and a soda" that would be somewhat repetitive. It is much easier to read a sentence that says "Alex went to the movies and he got popcorn and a soda." The pronoun he replaces the noun Alex.
Indefinite pronouns, on the other hand, take the place of a noun, but not one particular noun. In other words, the pronoun is there, but the "Alex" part of the sentence is not. Here are some examples of indefinite pronouns to help make this idea even clearer.
Examples of Indefinite Pronouns
All are welcome to come to the birthday party tonight.
Lizzie gave that book to someone and never got it back.
Anyone can play the game as long as they follow the rules.
Does anybody have a clue where the dog went?
Everyone knows it is impolite to point at someone.
No one came forward to admit the crime, so the whole class was punished.
Everyone had a great time at the Christmas party.
At the Thanksgiving dinner, each brought a plated dish to make the meal complete.
Marie told nobody the secrets that went on at her house.
Someone called to tell me the horrible news.
Although it could have happened to anyone, it happened to me.
When I looked around the house, I did not see anything out of the ordinary.
During my trip to the mall, I did not see anyone I knew.
I knocked on the door, but there was not anybody there.
Some will do anything to gain the attention of others.
Someone walked past the window and shouted.
Anyone in their right mind would know better than to do that.
Michael walked in and handed the piece of paper to someone.
Anyone would have agreed the woman in the black dress was gorgeous.
Some have the power to coax others to do what they want while others lack the power to do anything but follow.
After I painted my walls a deep shade of purple and installed jet black carpet, my room may be considered too gloomy for some.
I really just needed some time away from everyone.
After the story of the plane crash hit the news, many called for information on loved ones aboard the flight.
Sometimes I wonder why anyone shops at this store.
Very few came to visit the crabby old woman on the corner, leaving many to wonder if anyone cared about her at all.
If anyone cared about her, they certainly had an odd way of showing it.
Does anybody know a good place where I can go to get my nails done?
Normally during the holidays, everyone leaves campus.
I was told not to worry and that everything would be taken care of.
One of the great things about that cabin is that everything is included.
Anyone can plainly see that she was asking for trouble.
Anybody who came along would know something awful has happened here.
Everyone wandered aimlessly down the street wondering what would become of the space ships that occupied the otherwise clear blue sky.
I needed to see if anyone was interested in dating my cousin.
Someone really needs to come and mow my lawn.
Is anyone available to babysit for me on Tuesday?
My parents always told me that anything is possible.
Everyone enjoyed the food and the company.
Anyone that has ever lived in the city will never take for granted the peace of the country.
Someone whispered in my ear, but when I turned around there was not anybody there.
Few came to the wedding after the bride had a melt down and lashed out at her family and friends.
Everyone at the wedding could see how happy he made her.
After the festivities, everyone was invited back to the house for the after-party.
Some just do not know when to quit while they are ahead.
Someone should sue the pants off of that guy!
Anything is possible as long as you put your mind to it.
Mary wanted some, but I do not have any.
Someone drank all the soda.
Can anyone tell me why it is raining again?
Everybody loves to eat chocolate.
No one likes to eat vegetables.
Someone will clean up the kitchen.
No one was home at the neighbor's.
Everyone brought canned goods to the charity drive.
All were late to the party.
All of these sentences contain indefinite pronouns - it does not matter what specific person is doing the action. Indefinite pronouns are used in sentences every day and they are an important part of the English language.