Sometimes, the world of grammar can be as clear as mud. To some extent, once you get past a certain age, your use of the English language becomes largely instinctive, and then, all of a sudden, some teacher is trying to slap labels on parts of sentences and make you remember them all.
To make it worse, sometimes, people use different terms to refer to the same thing. Subordinate clause? Restrictive clause? Independent clause? Santa Claus? It can all be a jumble. Luckily, I’m here to help.
Clause for Confusion
Let’s start with the basics: Independent clauses and dependent clauses.
An independent clause is basically a sentence: It has a subject and a verb (and usually an object), and it can stand all by itself and make sense. “Mike ate grapes for lunch” would be an independent clause.
A dependent clause, which is also called a subordinate clause, comes attached to an independent clause in a sentence — it depends on the independent clause for context, and it doesn’t make sense all by itself. Look at this sentence:
“Since he wasn’t that hungry, Mike ate grapes for lunch.”
If you remove the first clause and write “Mike ate grapes for lunch,” that would make sense. But you couldn’t remove the second clause and just say, “Since he wasn’t that hungry.” It’s not a proper sentence: It adds explanation to something, but the thing that it’s explaining is missing.
Leading the Clause
A dependent clause usually starts with one of two things: a subordinating conjunction or a relative pronoun. Examples of subordinating conjunctions include “after,” “although,” “because,” “since,” “unless,” and “while.” Relative pronouns include “who,” “which,” and “that.”
In particular, two of those relative pronouns are often confused, “which” and “that.” They each have their own proper use — but which should you use, “which” or “that”? Learning a bit more about clauses can clear that up.
Dependent clauses come in two forms: restrictive clauses and nonrestrictive clauses. (These are also sometimes called essential clauses and nonessential clauses.) Neither type can stand on its own as a sentence, but a restrictive clause is one that’s necessary to add meaning to the independent clause in the sentence. A nonrestrictive clause, on the other hand, adds detail but isn’t really necessary — the independent clause would still be clear without it.
Clause and Effect
Let’s look at some examples:
“The Beatles song that I like best is ‘Paperback Writer.’”
In this sentence, “that I like best” is a restrictive clause. If we took it out, we’d just have “The Beatles song is ‘Paperback Writer,’” and that removes the whole point of the sentence — I’m telling you the song that I like, not just that a song exists.
“The movie, which is two hours long, stars Liam Neeson.”
Here, you could take out “which is two hours long,” and the sentence would still carry its central meaning: “The movie stars Liam Neeson.” Therefore, “which is two hours long” is a nonrestrictive clause, an additional but nonessential detail.
Did you notice something about those two clauses? The restrictive one started with “that,” while the nonrestrictive one started with “which.” That’s a good rule of thumb to use: If you could remove the clause without taking out an important thing that’s central to the meaning of the sentence, it’s a nonrestrictive clause and should begin with “which.” It should also be separated from the rest of the sentence by commas. If the clause is key to the meaning of the sentence, it should begin with “that” and not be separated from the rest of the sentence by commas.