What is an intellectual concept that you find stimulating and what does it tell us about you?

First introduced to the concept in world history class, existentialism fascinates me. Existentialism dictates that every person has an individual sense of truth and free will they are able to act upon candidly. Yet, as a society, we all abide by secular rules despite our human nature. Existentialism is like being 18 years old, but living in your parent's house- you legally have the freedom to do as you please, but you obey your parent's rules because it's their house. I enjoy studying human behavior, and it's interesting to see how people change their habits to parallel societal norms.

Any help on grammar, mechanics, or ideas in general would be much appreciated!
(Please keep in mind there is a 100 word limit.)

First introduced to the concept in world history class, existentialism fascinates me. I was first introduced to the concept of existentialism in world history class, and I became immediately fascinated.

Existentialism dictates that every person has an individual sense of truth and free will they are able to act upon candidly .

This is a good start to explaining existentialism. But maybe you could add more about the history. When did it start? Who started it? Where did it start? How did is spread?

A good thing to ask is the 5 W's and H questions. Who, what, when, where, why, how? Answer all of these in as much detail as you can and you have a good descriptive essay.

As I was First introduced to the concept in of existentialism in world history class, it fascinated me.

Existentialism dictates that every person has an individual sense of truth and free will they are able to act upon candidly.

Yet, as a society, we all abide by secular rules despite our human nature.

Existentialism is like being eighteen years old, but living in your parent's house.

You legally have the freedom to do as you please, but you (must) obey your parent's rules because, it is their house.

I enjoy studying human behavior. and

It is interesting to see how people change their habits to align parallel with societal norms.

Great start! I just shortened and cleaned up some of your sentences, overall you have a good point. I enjoyed the read. I would love to read more concrete examples, I hope my edits and suggestions help!