Google uses an algorithm to determine the search engine results (SERPS). The algorithm is based upon certain factors that include keyword density, Meta Tags, anchor tags, image tags, back links, etc etc etc.
If your site is optimized for specific keywords than you will rank better in the search engines. There are many factors but onsite optimization is a must. You can research and fine out the information yourself or hire and SEO. I have put together some Free Basics on http://www.seo4dummies.com
Overture shows you the bid price of certain keywords. Wordtracker show you the amount the term is searched. You can use http://www.nichebot.com a free tool to see all this at once.
You can research keywords free online with these various tools.
http://www.nichebot.com ( my personal SEO Favorite)[http://www.webmasterautomation.com/cgi-bin/keywordtool.cgi]
http://www.keyworddensity.com ( Keyword density analyzer )
AdSense / Adwords.
Google AdWords have a bid price to display certain keyword terms. Think of AdWords as TV commercials. Webmasters can put AdSense on there websites. Think of AdSense as the TV Program. If a viewer of your webpage clicks on one of your ads, you get a commission. That commission is based upon the price of the Adword. Google keeps about 60% of the bid price and passes about 40% to the webmaster or AdSense account.
The way the AdSense ads are displayed is determined by the Keyword Density of your individual sites. If you site is prominently about say Dogs then the AdSense will display ads about Dogs. However, Google in its new business model is now tracking IP numbers and providing more local ads. Think of the local TV commercials. They are not as expensive as the National Ads. Therefore you may have local ads that are displayed on your site that have only a$0.03 payout rather than a $5.00 payout.
If you optimize you site for your theme, or content, then you can generate more traffic to you sites based upon your keywords. The Google Adsense, will display ads relevant to your topics. If they are not displaying ads to our topic, then you must adjust your Density of your keywords in the body of text of the page.
Search Engine Optimization (SEO) is the practice of changing your website, so that it is spider friendly. If your site is brand new it will take a few months for Google to index your site and be visible in the SERPs. This is known as the Google sandbox theory. Aged sites should already be indexed as long as the site has something for the spiders to grab. Excessive graphics, java scripts, PHP sessions are all not spider friendly.
To get spiders to come to your site often and grab your data, you must have links from outside websites to your site. This is the Coveted Page Rank factor. Page rank is only a factor of the amount of incoming and outgoing links to your site. Only a small percentage of Page Rank is attributed to the Google Algorithm for Search Engine Results at this time.
Spiders follow links, once there are links established the spiders will Crawl, your sites. They will gather minimal information. Several Weeks to months later, the spiders will Deep crawl you site and index all that is available. To speed this process along, back links or links to other sites is a must. The more links the spider can travel to get to your site the better. Linking to like minded topics is always best. You dont need to buy LINKS. You can acquire links via posts in forums, writing and submitting articles, using a Blog post, submitting to SEO friendly directories.
To view the spider activity on your site, first go to your traffic stats. Look for the googlebots. See how often they come and the amount of data they have grabbed. You can also go to Google itself and if you are indexed view the Cache of your page. That cache date is a good indication of the last true crawl of your site.
To see if you are indexed go to Google and type in the search box, site:www.yourwebsite.com ( make sure the word site is not Capitalized and you replace he words your website with your actual URL). View the results. You should also repeat the process and this time leave out the www. , and just enter the site:yourwebsite.com
Sometime webmasters leave out the www., but then look for Google using the www. Or link to sites using the www. Either way is fine, just pick one version and be consistent with www. Or non www throughout your website career.
As the spiders come to your site they will start to grab information, that information is sorted and returns the SERPS. Did you know that there are different DataCenters throughout the world that Hold that information? If you ask a friend on the say East Cost to search for a term and tell you where you site is in the SERPS, they result on the West cost may be completely different. As much as 5-10 or more positions depending on the activity of that keyword.
OK thats enough for today.