The pie that is chocolate is missing a piece.
The pie, which is chocolate, is missing a piece.
Besides making you hungry, the two sentences have a lot in common; however, they also have some important but subtle differences. It’s learning the subtle differences that can help you use the words that and which correctly. For example, the first sentence about the chocolate pie implies there is more than one flavor of pie, but only the chocolate pie is missing a piece. The second sentence states that there is only one pie and it has a piece missing. It also offers a side note to let you know that the pie is chocolate, but that fact is not considered as important as the fact that a piece is missing. (Obviously the second sentence wasn’t written by a chocoholic.)
The word that introduces restrictive clauses, or clauses that supply essential information to the intended meaning of the sentence. This is information that the reader needs to know to understand all that the sentence states and implies. However, the word which introduces non-restrictive clauses, or clauses that supply non-essential, supplemental information to the sentence, and if left out won’t change the sentence’s meaning (stated or implied). When trying to decide whether to use that or which, ask yourself these questions:
If I take out the clause, does my sentence’s meaning remain the same? If it does, you should use which; if it doesn’t, then use the word that.
Does the sentence feel as if it needs a comma? If so, this might indicate that you need to use the word which, because the clause it introduces is preceded by a comma. (The pie, which is chocolate, is missing a piece.)
So, when you’re putting together your sentence and wondering if you need to put in a that or a which, you need to think about what the point of the sentence is. What is it that you want the readers to know—do they need to know that a piece of pie is missing, or that a piece of chocolate pie is missing. Now, before you run out and get yourself a piece of chocolate pie, try the short quiz I’ve included below.
The four sentences below need either the word that or which. Determine the word needed based on whether the adjoining information is necessary for the reader to understand the message or whether the information is just nice to know.
Note: Remember to place a comma before any clause introduced by which.
- The user guide should only contain instructions [that/which] were verified.
- The application requires a logon and password [that/which] prevents unauthorized access.
- The report shows every account [that/which] has been closed in the past 30 days.
- They canceled yesterday’s ABC project meeting [that/which] was already rescheduled twice.
The answers and explanations are below:
- The user guide should only contain instructions [that/which] were verified. The information “…that were verified” tells us exactly what type of instructions. You need the additional information to clarify the sentence; therefore, you need to use that.
- The application requires a logon and password, [that/which] prevents unauthorized access. The information that the logon and password prevent unauthorized access is interesting, but it isn’t essential; therefore, you need to use a comma and the word which.
- The report shows every account [that/which] has been closed in the past 30 days. Because the report is only showing accounts that were closed in the past 30 days, you need to use that; otherwise it would read as if the report were showing every account.
- They canceled yesterday’s ABC project meeting, [that/which] was already rescheduled twice. The information about the meeting being rescheduled twice is not essential to understanding that the ABC project meeting was canceled; therefore, you need to put in a comma and use which.
So, now go ahead and get that piece of pie.