If you’re looking to clarify your writing and make it as clear as possible, it’s important to understand the difference between which and that. Both words function as relative pronouns, but which and that differ in their meanings.
Which is used to introduce non-essential clauses, and that is used to introduce essential clauses. In this Grammarly article, we’ll discuss when to use each word, as well as how to avoid common mistakes.
1. Restrictive Clauses
For many people, understanding the difference between which and that is a difficult task. It’s not helped by the fact that English grammar has evolved over time, as well as the fact that different style guides and regional dialects use the words differently.
Which is often used to introduce restrictive clauses, which are necessary for the meaning of a sentence and can’t be removed without altering the sentence’s meaning. For example, he is looking for his high school report cards which are in the basement.
Nonrestrictive clauses, on the other hand, add extra information that isn’t essential for the meaning of a sentence and can be easily removed without changing its meaning. For example, he is looking his for his high school report cards that contain soybeans. These clauses can be seen as being similar to a silk scarf, which you may wish to wear but isn’t really necessary for your day-to-day life. You may also consider using the mnemonic device of remembering that for restrictive and which for nonessential clauses.
2. Nonrestrictive Clauses
When a nonrestrictive clause is not bounded by commas, parentheses, or a dash it can be introduced with which. These types of clauses add descriptive elements to the noun they modify, but they can be removed without changing the meaning of the sentence.
While the difference between which and that may seem minor, it is a very common grammar mistake to make. It’s important to understand when to use each so that your writing is clear and easy to read.
While some grammarians suggest using that to introduce nonrestrictive clauses, it’s generally a good idea to use which if the clause can be easily removed from the sentence without changing its meaning. It’s also a good idea to avoid using which and that with personal pronouns when referring to people because this can be confusing for readers. Instead, use who when referencing people in a relative clause. For example: The children need sturdy shoes, but these are too expensive.
3. Relative Clauses
English grammar can be confusing. That’s especially true when it comes to rules about the relative pronouns which and who. These two words are often confused by writers, and they can even be used interchangeably in some sentences. Whether or not this is allowed by the grammar rule book depends on the context of the sentence and the writer’s style.
These two words are found in relative clauses, which are subordinate clauses that function as adjectives. They are usually followed by the word who, whomever, or whose. These pronouns are not used to refer to people; instead, they are used to describe objects, places, or ideas.
If the relative pronoun starts a nonessential clause that provides just additional information about a noun in the main sentence, it should be set off with commas. But if the relative pronoun heads a defining clause, it should be left intact. It’s best not to mix up these constructions and risk a confusing read for your readers.
4. Interrogative Clauses
The difference between what and which may seem minor, but it can make a big difference to your readers. Knowing when to use which and when to leave that out can help you write clearer sentences.
While the rules for what and which aren’t quite as firm as other grammar rules, it’s still important to follow them. Which should be used for nonrestrictive clauses, while that should be reserved for restrictive clauses.
Using these words incorrectly can confuse your readers and prevent them from understanding the meaning of your sentences. Often, this confusion comes from using that and which to fill in spaces in long, complex sentences or from trying to use too many fancy words to satisfy word quotas at school. Whether you’re an amateur or an experienced writer, keeping these rules in mind will help you make your writing more concise and clear.