I'll lead with an apology: I got ambitious. You said you wanted to know about particles; I wanted to say a lot about them, so I guess I wrote a book.

Also a disclaimer: I only had physics through undergrad. My source is Sections 1 through 3.1 in Baez, J., & Huerta, J. (2010). The Algebra of Grand Unified Theories. Bulletin of the American Mathematical Society, 47(3), 483–552. if you want to consult something more reliable.

Introduction

If you look inside a bakery, you will find lots of different ingredients—flour, sugar, butter, milk, eggs, and so on. By combining these ingredients in different ways, the baker can make all kinds of different breads and desserts. To make the kind of food they want, the baker has to understand their ingredients, how much of each kind to use, and how to combine them.

In the same way, we know that everything in the world can be made out of different kinds of very tiny ingredients called elementary particles. By combining these particles in different ways, we can create all kinds of stuff. But to make the stuff we want, we have to understand the elementary particles and how they affect each other, just like the baker has to understand their ingredients and how they go together.

There are over one hundred different kinds of elementary particles that we know about and maybe more that we don't. We could just memorize them all, but scientists think it's better to look for patterns. Think about when you were learning addition: its easier to learn that zero plus anything is always the same thing than it is to memorize 0 + 0 = 0, 0 + 1 = 1, 0 + 2 = 2, 0 + 3 = 3, and so on. Scientists do the same thing; they find patterns. Eventually they wrote down all of the elementary particles that they had discovered and all of the patterns they were really sure about. They called this knowledge "The Standard Model".