Query Mapping is the process of identifying and controlling which campaigns / ad groups / keywords search queries are showing in. The goal is to have a perfect 1:1 ratio, but that is almost never possible due to things like closer variants and Google selecting their favorite keywords based on performance. That 1:1 ratio means when a user types in a search query, there is only one possible keyword or ad group in the account what it will match for.
Being able to narrow down the amount of areas that a search query will match allows the marketer to control messaging, control budget to that keyword, and collect performance data faster for a specific query.
Here is an example of an account where a search term was matching for four different keywords, none of which are related to “Mississippi” or “river cruises” specifically.