A sentence is a single complete thought.

I hate fish.

The single complete thought is “I hate fish.”

Now, we’ll make it a bigger sentence:

I hate fish because I break out in a rash.

Still a single thought. Still a sentence. You’re just explaining it a bit more.

You don’t do this:

I hate fish because I break out in a rash and all sorts of terrible things happen because I really hate eating fish and did I tell you about the time I ate a fish and it really turned out badly?

That’s called a run-on sentence and it is terrible. Write your thoughts one at a time, each in their own sentence.

A sentence usually has at least two things: something spoken about and something said about it.

John ran.

John is being spoken about and ran is what is being said about John.

However, there is such a thing as a one-word sentence, usually used in fiction or casual writing:

Do you like cats? Yes!
He hit the ball. Hard.
Home. That’s how Kansas felt to her.

Let’s talk about paragraphs
A paragraph is a bigger thought than a sentence but is all one thought.

“I hate fish because I break out in a rash when I eat it. One time, I was in Hawaii and ate a fish, and I had to run to the pharmacy to get medication. Let me tell you: I hate fish!”

This is a complete thought on the subject of “disliking fish.” It’s a bigger thought that just “I hate fish.” But it’s all the same idea, and that’s a paragraph. It’s all the same big thought.

Let me show you how it wouldn’t be done:

“I hate fish because I break out in a rash when I eat it. One time I was in Hawaii, and ate a fish, and I had to run to the pharmacy to get medication. Let me tell you: I hate fish! One day I was wearing pants and didn’t like the color. So I decided it had something to do with my dislike of fish. I started only buying pants that were not anywhere near the color of a fish, but then I came to realize, fish come in every color imaginable. So now I don’t wear pants!”

Look at what happened: the reader is completely confused, with two different big thoughts joined together. First, it’s about hating fish, and then, there’s this whole separate idea about pants.

If I had just split the ideas out into two paragraphs, it would have made sense.

I recommend keeping your paragraphs short. Long paragraphs are boring and difficult to follow. Ideally, keep your sentences short as well.

Put a space between your paragraphs
This seems like something very simple, but in emails, I often see paragraphs written without any spaces between them. Just press the big Enter key on your keyboard to make one, nice, fat space between the paragraphs.

Clauses (stay with me here)
You can skip this part, but you might find it helpful.

Simple sentences are good, but sometimes they can be a bit boring. So, we might want to make them more interesting by adding more.

To do this, we join groups of words that are each “mini-sentences,” into one sentence to make a more complex, richer thought.

Each of these groups of words is called a clause. Clause comes from a Latin word meaning “a brief statement.”

Clauses are a source of considerable confusion for people, and that’s not their fault. It’s been made very confusing.

I’m going to try and make it very simple: There are two main types of clauses – those which express their own complete thought, and those which rely on another clause.

Clauses that express their own complete thought are called independent clauses. Clauses which rely on another clause are called dependent clauses.

Let’s start with a simple sentence:

I love cats.

That is a complete thought, but you want to say a bit more. So you add “because they are so cuddly.”

I love cats because they are so cuddly.

“Because they are so cuddly” depends on the other clause. It can’t stand on its own. It’s a dependent clause.

Let’s go back to a simple sentence:

I love bicycles.

In this case, you want to add that you dislike motorcycles. So you add “I dislike motorcycles”:

I love bicycles, but I dislike motorcycles.

These are two independent thoughts, each independent clauses. They can stand on their own. To make the writing understandable, they are joined by a conjunction, a word that joins clauses (the word but).

That’s it. End of lesson. If you want to study more about clauses, get a good grammar book. But I do not want to kill you with this information. I want you to live.