Use a comma with conjunctions between two independent clauses.
The Short Story
Use a comma with a conjunction between two independent clauses in one sentence. To help us visualize this, the independent clauses will be blue, and the comma and conjunction will be yellow.
Ex: The dog quickly grabbed the ball, and it ran to the other side of the field.
“The dog quickly grabbed the ball” is an independent clause because it could be its own full sentence. “Then it ran to the other side of the field” can also be its own sentence. The comma and conjunction are used correctly here.
The Novel
An independent clause is a part of a sentence that can be its own sentence, meaning it can stand on its own if it is taken out of its original sentence. An independent clause must have a subject and a verb—just like a complete sentence needs a subject and a verb.
Ex: I go to parties every weekend because I love to dance.
In this example, “I go to parties every weekend” can stand on its own. So, it is an independent clause. But “because I love to dance” cannot stand on its own, it is not an independent clause. This means that we do not add a conjunction and a comma. Remember, we need two independent clauses.
We can combine two independent clauses in one sentence by connecting them with a comma and a conjunction. If you need a reminder on the conjunctions used to connect two independent clauses, just remember FANBOYS:
Ex: I go to parties every weekend, and I love to dance.
Because “I go to parties every weekend,” and “I love to dance” are independent clauses, we will always join them with a comma and a conjunction.
Let’s look at some more examples.
Ex: He spent all of his money, so he couldn’t buy the tickets.
“He spent all of his money” and “he couldn’t buy the tickets” are both independent clauses connected with the conjunction “so” and a comma.
Ex: The cat grabbed the mouse but didn’t eat it.
“The cat grabbed the mouse” is an independent clause but “didn’t eat it” is not. Even though there already is a conjunction in this sentence, we still don’t use a comma here because there is only one independent clause.
The Examples
“It can be easy to fall in love with the initial version of your idea, but great ideas always evolve.”
(Clear, James. “For a More Creative Brain, Follow These 5 Steps.” James Clear, 8 June 2018, jamesclear.com/five-step-creative-process.)
“It can be easy to fall in love with the initial version of your idea” and “great ideas always evolve” are both independent clauses, so a comma and a conjunction connect them.
“From 1986 to 2011, Oprah Winfrey hosted The Oprah Winfrey Show. It was the highest rated talk show of all-time and familiar to nearly anyone who owned a television set in North America at that time.”
(Clear, James. “The Surprising Benefits of Journaling One Sentence Every Day.” James Clear, 14 Jan. 2019, jamesclear.com/journaling-one-sentence.)
“It was the highest rated talk show of all-time” is an independent clause but “familiar to nearly anyone who owned a television set in North America at that time” is not, so no comma would be used here.
“African languages, however, are among the fastest-growing languages with regards to the speed of growth, and the continued flow of Africans Westwards remains significant to the trend.”
(Nwoye, Chidinma Irene. “African Languages Are the Fastest Growing in the United States2.” Quartz, Quartz, 2019, qz.com/africa/1723269/african-languages-are-fastest-growing-in-the-united-states/. )
“African languages, however, are among the fastest-growing languages with regards to the speed of growth” and “the continued flow of Africans Westwards remains significant to the trend” are both independent clauses. So, a comma and a conjunction are used to combine them.