That vs. Which
Identifying a Noun With a Modifying Clause
Identifying vs. Nonidentifying Clauses
| THAT — AN IDENTIFYING CLAUSE | WHICH — A NON-IDENTIFYING CLAUSE |
|---|---|
An identifying (restrictive) clause adds information or restricts the noun to a specific one, group or lot. The clause helps by telling us which one, where or when. Either which or that can be used. The clause is not set off by commas. |
A non-identifying (non-restrictive) clause adds extra information about a noun already identified by other means, for example, by name, by shared knowledge or context.. The clause is just adding extra or interesting information. That cannot be used in a nonidentifying clause. It is set off with commas (parentheses or dashes.) |
The water that I drank last night contained sodium. (identifies the specific one) |
The Evian water, which I drank last night, contained sodium. (adds extra info) |
The car that runs off of a lithium-ion battery is surprisingly fast. |
The Tesla, which runs off of a lithium-ion battery, is surprisingly fast. |
The prison that was located in San Francisco Bay was a depressing place to work. |
Alcatraz Prison, which was located in San Francisco Bay, was a depressing place to work. |
lithium-ion battery (n.) – a type of battery used in laptops
depressing (adj.) – causing to feel sad
prison (n) – a building where people are kept as punishment for a crime

Methods of Identification
| MODIFIER | IDENTIFYING MODIFIERS | EXTRA IDENTIFYING MODIFIERS |
|---|---|---|
|
No comma is used when adding a clause that helps identify the noun. |
A comma is used when adding a nonidentifying clause (a clause that adds extra information.) |
(none) |
The store sells organic produce. |
Whole Foods sells organic produce. |
with a clause |
The store where I shop sells organic produce. |
Whole Foods, where I shop, sells organic produce. |
with a phrase |
The store on the corner of Channing and University sells organic produce. |
Whole Foods,on the corner of Channing and University, sells organic produce. |
with a name |
The store, Whole Foods, sells organic
produce. |
Whole Foods, a grocery store, sells organic
produce. |
by later mention |
The store sells organic produce. Whole Foods sell "green products" as well. |
– |
by earlier mention |
I like Whole Foods. The store sells organic produce. |
– |
by referring to some or all |
Whole Foods where shoppers can recycle bottles sells organic produce. |
Whole Foods, where shoppers can recycle bags, sells organic produce. |
by its uniqueness |
The moon is bright. |
The moon,
which is full tonight, is bright. |
NOTE: "where I shop" = "in which I shop" = "which I shop in" (informal)
Common Mistakes
| ERROR | FIX |
|---|---|
The London Bridge which it was in England is now in Arizona. |
The London Bridge, which was in England, is now in Arizona. |
The marine iguana that eats algae in the sea is only found in the Galapagos Islands. |
The marine iguana, which eats algae in the sea, is only found in the Galapagos Islands. algae (n.) – a simple plant without stems or leaves that grows in or near ocean water The type of iguana is identified. The modifying clause adds extra information. |
Alcatraz Island surrounded by fog was a depressing place to serve time in prison. |
Alcatraz Island, surrounded by fog, was a depressing place to serve time in prison. The type of iguana is identified. The modifying clause adds extra information. |
Practice
The San Francisco Bay Area
Join the two sentences into one. Decide whether to use commas with the clause:
- Select commas or no commas.
- Read the feedback about your option.
Index Grammar-Quizzes | Previous The X of which | Next Some or All

