For Google has Adwords these Adwords depends on keywords. There are many keywords available which we can get control over these keywords.It uses four different types of keywords they are broad, exact, phrase, negative these can be made combination with types of keywords they can add as group in the broad match the broad match keywords are symbols which can be Shown as keywords.
If there is any key word the key word not only searches for exact keyword it also searches for Adsense.