How does adding keywords affect AdSense for search?

Keywords are used by Google to make sure that we promote the most relevant ads and pages in the search results for your search engine. Good keywords are words and short phrases that describe any of the following:
The topic of your search engine
The content of the pages you want promoted
For example, a search for 'tiger' may yield different sets of results and ads depending on keywords entered.
Website Topic
Keywords
Results and Ads
Golf
golf, PGA, Callaway, US Open
more related to Tiger Woods
Mac
Apple, Mac, OS X
more related to the Tiger OS
Safari
Africa, wildlife, jungle
more related to the animal tiger