That vs. Which
From TechWriter Wiki
(Note that this page refers to the use of the words that and which when used as a join between two clauses.)
The words that and which are often used interchangeably (and some dictionaries and style guides do not offer a solid distinction), but there is a simple guideline that you can use in order to make your writing more intuitive - especially for readers for whom English may not be their first language:
If the second clause is a restrictive clause, then use that; otherwise, use which.
Here, a restrictive clause is one that is specifically required because the meaning of the first clause would be different if it was omitted.
Examples:
| Example | Explanation |
|---|---|
| UPK includes two features that you can use for organizing topics. | This wording suggests that UPK contains at least two features, and of these features, two of them can be used for organizing topics. Here, the second clause, "that you can use for organizing topics", refers directly to the object of the first clause, the features of UPK. If you omitted the second clause, then the sentence would be "UPK includes two features", which alters the meaning of the sentence. |
| UPK includes two features, which you can use for organizing topics. | This wording suggests that UPK contains only two features, and that both of these features can be used for organizing topics. Here, the second clause is nonrestrictive, because if you remove it then the sentence becomes "UPK includes two features" which would (if this is our intent) have the same meaning as the full sentence (that UPK contains only two features). Note that the use of a comma before which is not strictly required. However, it does serve as an additional cue for the reader as to the meaning of the following clause. |
It is important that if you adopt this convention that you use it consistently throughout your document (or documentation set).
