Google has recently filed a patent regarding the handling of keywords on web pages.
This patent describes a method where website owners can view the primary keyword phrases that Google assigns to their websites. Google identifies the most important keywords for a site using a phrase-based indexing system, and website owners can add other relevant keywords.
How does Google find the primary keywords for a website?
All major search engines index web pages based on individual words. If certain words and phrases appear together on the same page, the search engine will assign a theme related to those words. For example, "Paris" and "Hilton" are associated with a person rather than a city or hotel, while "tiger" and "forest" are linked to golf.
Google's patent indicates that it will inform you of what it considers to be the primary keywords for your site and suggest modifications.
How does Google determine the relationships between phrases?
Google's index contains billions of web pages. If Google finds many pages containing both "Paris" and "Hilton," it will infer that these keywords are related. Other words on these pages may give Google a hint that this specific combination refers to a person.
If a word frequently appears near other groups of words, they are considered closely related. Google has numerous algorithms that calculate the relationships between different groups of words.
What does this mean for your website?