# Introduction and Monoids

## Course: Category Theory from the Universe Up

Many people are intimidated by Category Theory and I was one of them. But I braved the waters and found some pretty cool stuff there. I'd like to share some of it with you.

## Introduction

Many people are intimidated by Category Theory and I was one of them. But I braved the waters and found some pretty cool stuff there. I'd like to share some of it with you. Category theory is just math, and math is a way we have to describe things we experience every day in the world. So it's a shame that it's often taught the way it is. Because it is often taught in a bad way, an intimidating way, I would dare say a snobby way.

I want to teach Category Theory as a real thing in people's lives. Categories, like any branch of math, is an expression of discoveries about the structure of the universe. In teaching it, I'd like to answer the following questions:

- If category theorists say that category theory underlies much of what we do as programmers, why do programmers find the ideas so foreign?
- Why is category theory so abstract?

## Monoids

My favorite category to explore at the moment is the category of monoids. They're everywhere in our world. I'd like to give a few example operations and show how monoid abstracts them.

The examples:

- Piling rocks
- Making trains
- Merging hashmaps