Based on what kind of information an interrogative adverb inquires about, they are categorized into four main groups:

The interrogative adverbs of time are words that demand time-related information and ask how long, how often, or in which exact time something takes place. Here are a few examples:

Here is a list of interrogative adverbs of time:

Interrogative adverbs of place ask about the location or place of something. One of the most commonly used interrogative adverbs of place is 'where'. Let us take a look at the examples:

Here is a list of interrogative adverbs of place. Most of these interrogative adverbs can be used to ask about a physical place as well as an abstract source or origin.

The interrogative adverb 'why' is used when you want an explanation or reason for something. It is commonly used to ask questions about the cause or motivation behind an action or event. Here are a few examples:

Here is a list of interrogative adverbs of reason:

The interrogative adverb of manner is the word 'how' which is commonly used to ask questions about the method, process, or means by which an action is performed. Check the examples:

'How' can also be used with an adjective or adverb to ask about the degree or extent of that adjective or adverb. Here are some examples:

To make direct questions with interrogative adverbs all you have to do is use an auxiliary after the interrogative adverb. In other words, a yes/no question follows the interrogative adverb to form a wh-question. Look at some examples:

There are two forms of indirect questions in English:

To turn a question into a statement, you can use a declarative sentence with an interrogative adverb embedded within it. The verb 'ask' is commonly used to introduce the question, but other verbs and phrases are also possible. In this structure, there is a period at the end of the sentence and the question does not involve inversion. Here are a few examples:

When we use an interrogative clause in the form of a yes/no question with another question using an interrogative adverb embedded within it, we are creating an indirect question within a direct question. In this case, a question mark is used at the end of the sentence but still no inversion is necessary. Here are the examples:

Interrogative determiners (what, which, whose) modify a noun, and they are followed immediately by the noun; but interrogative adverbs are used on their own and do not modify a noun. Here are a few examples:

Interrogative pronouns are used to ask about people, things, and options, while interrogative adverbs are used to ask about aspects such as place, time, manner, and reason. Compare the examples:

An interrogative adverb can also be used as the head of a nominal clause which is used as the object of a transitive verb such as know, wonder, ask, suppose, etc. Check out the examples: