Conjunctions are an important part of English grammar, connecting words, phrases, and clauses to create fluid, meaningful sentences. They are one of the most essential word classes in English yet can often cause issues. This is especially true for authors writing in English as a second language. The syntactic differences between their native language and English, and the nuances required of formal, academic writing, can lead to mistakes with conjunction usage that are otherwise easy to correct.

In this article, we will explain what conjunctions are, making sure authors understand the differences between coordinating, subordinating, and correlative conjunctions in the process.

What are conjunctions?

Conjunctions – also known as connecting words or linking words – are words that connect to other words, phrases, and clauses within a sentence. These connections bring together ideas between different sentence elements of the clauses, allowing for complexity and meaning to be communicated. Common conjunctions include and, but, or, because, etc.

Without conjunctions, writing would sound like a series of incomplete thoughts with no logical links between sentence units. When used appropriately, conjunctions help us demonstrate contrast (although, but, yet); choices, reasons, and cause and effect (because); and links between events or additions (and), among other things.

Different types of conjunctions and examples

There are three main types of conjunctions:

• Coordinating
• Correlative
• Subordinating

Coordinating conjunctions

Coordinating conjunctions join words, phrases, and clauses of equal grammatical rank in a sentence. The most common coordinating conjunctions in English are for, and, nor, but, or, yet, and so. The acronym FANBOYS is a useful way to remember these key conjunctions.

Here is an example of how a coordinating conjunction connects two nouns of equal grammatical rank, soil and moss:

• We tested water absorption in soil and moss.

If two independent clauses are being connected by a coordinating conjunction, then a comma is required before the conjunction:

• Participants were asked to remain seated during the study, and observations were recorded every five minutes.

For coordinating conjunctions to work, the words or phrases being connected must be parallel (i.e., have the same grammatical structure). The first example is incorrect, whilst the second is correct:

• Well-being assessments were conducted regularly and efficient.
• Well-being assessments were conducted regularly and efficiently.

Correlative conjunctions

Correlative conjunctions are pairs of conjunctions that function to frame and connect grammatically identical sentence elements. Common correlative conjunctions include either/or, both/and, neither/nor, and not only/but also.

Correlative conjunctions must be paired correctly; if a noun follows both, then a noun must also follow and:

• Both the methods and results are discussed below.

Subordinating conjunctions

Subordinating conjunctions connect dependent clauses with independent clauses, demonstrating relationships of cause and effect, comparison, contrast, etc., between clauses. Common subordinating conjunctions include because, although, though, as, until, whilst, and whereas. These conjunctions introduce a dependent clause that needs the independent clause of the sentence to produce meaning:

• We ended the third round of testing prematurely because of time limitations.

Here, the subordinating conjunction because makes the clause because of time limitations dependent on the context of the independent clause, and vice versa, to make the meaning of the sentence clear.

Subordinating conjunctions do not necessarily have to go between the two clauses, like in the above example. They must introduce the dependent clause, but the dependent clause can come before the independent clause. If the dependent clause comes first, a comma is used before the independent clause.

• Because of time limitations, we ended the third round of testing prematurely.

Common mistakes

Conjunctions can cause issues for authors, especially those unfamiliar with English grammar. Therefore, it is important for authors to familiarise themselves with common mistakes in the use of conjunctions.

Comma splices

One of the most common mistakes is comma splices. A comma splice is when a comma is used to join two independent clauses incorrectly, i.e. without a coordinating conjunction or proper punctuation.

• We used laboratory equipment for testing, we also used the cleaning solutions provided by the laboratory.

Here, a coordinating conjunction after the comma separating the independent clauses is necessary.

• We used laboratory equipment for testing, and we also used the cleaning solutions provided by the laboratory.

Incorrect correlative pairs

Although correlative conjunctions must match, sometimes authors do not follow this rule.

• Neither the first group or the second group showed signs of sleep deprivation.

Here, neither/or is not a correct correlative pair. The pair must match (neither/nor).

• Neither the first group nor the second group showed signs of sleep deprivation.

Lack of parallel structure

The use of coordinating conjunctions requires the same grammatical form to be used when joining items, which can confuse some authors.

• After use, the devices were assessed immediately and with care.

Here is the correct way to ensure the same grammatical form between items joined by a coordinating conjunction:

• After use, the devices were assessed immediately and carefully.

This list of common mistakes is not exhaustive, but it should give authors a clearer idea of what to be wary of when using conjunctions in English.

Getting help with conjunctions

Knowing the different types and functions of conjunctions is key to ensuring your scientific paper is ready for publication. If you struggle with conjunctions or English grammar more broadly, professional editing services can help.

At MDPI Author Services, we specialise in helping researchers prepare their manuscripts for publication. Our Figure Editing Service provides publication-ready figures that clearly communicate your research to readers. Figure editing enhances your charts and graphs by revising the colours, shading, size, resolution, borders, font, and file type. This is all completed in one business day after payment. Click here for a free quote.

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