WHO: The term 'who' is used to refer to a person or persons, typically in the context of asking a QUESTION. It is often used to ask for the identity of someone or something, such as 'Who are you?' or 'Who wrote this book?'. It can also be used to ask for the origin of something, such as 'Who invented the telephone?'. WHAT: The term 'what' is used to ask for information about something, typically in the form of a QUESTION. It is often used to ask for the nature or characteristics of something, such as 'What is your favorite color?' or 'What is the capital of France?'. It can also be used to ask for the purpose of something, such as 'What is the purpose of this tool?'. WHEN: The term 'WHEN' is used to ask for information about the time of an event or occurrence, typically in the form of a QUESTION. It is often used to ask for the date or time of something, such as 'WHEN did the Civil War begin?' or 'WHEN is your birthday?'. It can also be used to ask for the frequency of something, such as 'WHEN do you usually go to the gym?'. WHERE: The term 'WHERE' is used to ask for information about the location of something, typically in the form of a QUESTION. It is often used to ask for the physical location of something, such as 'WHERE is the nearest grocery store?' or 'WHERE is the Eiffel Tower?'. It can also be used to ask for the source of something, such as 'WHERE did you get that shirt?'. WHY: The term 'WHY' is used to ask for information about the reason or cause of something, typically in the form of a QUESTION. It is often used to ask for the purpose of something, such as 'WHY did you do that?' or 'WHY is the sky blue?'. It can also be used to ask for the explanation of something, such as 'WHY is this rule important?'.