Relative adverbs are adverbs that introduce relative clauses. Relative clauses are also called adjective clauses since they function as adjectives. Relative clauses are dependent clauses, which means they cannot stand alone as a sentence. Relative adverbs connect, or “relate,” a dependent relative clause to an independent clause. The three relative adverbs are when, where, and why. As you can tell by the words themselves, relative adverbs relate information regarding time, place, or the reason for something. In each example below, the relative adverb is underlined the entire relative clause it introduces is italicized.

When is used to connect a relative clause describing a time or event.

Do you remember that time when Jack climbed up to the roof?
I clearly recall the day when I broke my nose.
That was the moment when I knew I wanted to study medicine.

Where is used to connect a relative clause describing a location.

The town where I grew up is really beautiful this time of year.
Did you like that restaurant where we got the chicken and pizza?
I remember the place where we saw the deer last week.

Why is used to introduce a relative clause relating to the reason for an action.

Do you know the reason why we have to follow these strange guidelines?
That is the reason why I never take my phone out of its case.

The word reason is often left out, but the sentence still means the same thing because why already implies a reason. When reason is omitted, the adjective clause is still considered to be modifying the implied reason.

Do you know why we have to follow these strange guidelines?
That is why I never take my phone out of its case.

---