Relative Pronouns: That for People or Things

Relative pronouns like that function as a bridge. This bridge connects a main clause to a descriptive clause. Usually, you have two separate thoughts. Thought one: "I bought a laptop." Thought two: "The laptop is very fast." To combine them, you use that. It replaces the repeated noun. So, it becomes: "I bought a laptop that is very fast." In this sentence, that is doing two jobs. It is standing in for the word "laptop." It is also starting the new description. You don't need to say "it" or "the laptop" again. That handles everything for you. It can be the subject of the description. It can also be the object. It is a multitasking hero in the world of grammar.

1. 1Creating these sentences is like building with Lego bricks. Follow these simple steps:
2. 2Start with your main sentence (e.g., "I met a guy").
3. 3Identify the noun you want to describe (e.g., "guy").
4. 4Place that immediately after that noun.
5. 5Add your descriptive information (e.g., "works at the bank").
6. 6Check that you didn't repeat the noun.
7. 7Your final result: "I met a guy that works at the bank."
8. 8If that is the object, the pattern changes slightly.
9. 9Main sentence: "The pizza was delicious."
10. 10Noun to describe: "pizza."
11. 11Add that: "The pizza that..."
12. 12Add your description: "...you ordered."
13. 13Result: "The pizza that you ordered was delicious."

You should use that when the information is essential. This means the listener needs the info to understand which person or thing you mean. We call these "defining relative clauses."

• Identifying People: "The candidate that we interviewed yesterday was great." (This tells us which candidate).
• Identifying Things: "The car that is parked outside is mine." (This tells us which car).
• After Superlatives: When you use words like "the best" or "the only," that is the preferred choice. "This is the best meal that I have ever eaten."
• With Indefinite Pronouns: Use it after words like everything, something, nothing, or all. "Everything that she said was true."

Think of it like a spotlight. It shines a light on exactly which item or person you are talking about in a crowd.

There are a few places where that is not allowed. It is like a "No Entry" sign for grammar.

• After Commas: If you are giving extra, non-essential information, do not use that. You must use who or which. For example: "My house, which is old, needs repairs." You cannot say "My house, that is old..."
• After Prepositions: You cannot put that immediately after words like in, on, or with. You wouldn't say "The chair in that I sat." You would say "The chair that I sat in."
• Formal Writing for People: In very formal academic papers, some people prefer who for people. But in 99% of daily life, that is perfectly fine for people.

Even native speakers trip over these sometimes. It is like a grammar banana peel.

• The Double Subject: "The book that it is on the table is mine." (✗) You don't need "it." That is already the subject! Correct: "The book that is on the table is mine." (✓)
• The Comma Trap: Adding commas around a that clause. "The dog, that barked, was loud." (✗) That clauses never take commas. Correct: "The dog that barked was loud." (✓)
• Using it for Extra Info: "My mother, that is 60, loves gardening." (✗) Since this is extra info about a specific person, use who. Correct: "My mother, who is 60, loves gardening." (✓)

You might wonder: "When do I use who or which instead?"

• That vs. Who: Who is only for people. That is for people and things. In casual conversation, they are often interchangeable for people. "The girl who called" and "The girl that called" are both fine.
• That vs. Which: Which is only for things. Use which for extra information (with commas). Use that for essential information (no commas).

Think of that as the "Essential Worker." It does the hard job of defining exactly what we are talking about. Which is more like a "Tour Guide." It gives you extra facts you might find interesting but don't strictly need.