To understand why AdSense is crucial to the success your content-rich websites you must first understand how AdSense works.

The theory is very elementary, if you consider it. The website owner includes a piece of script within the code on their web pages and whenever the page is viewed, the script will draw in adverts from the AdSense program. Because of the way AdSense works, the advertisements which are shown will be relevant to the content of the page on which they appear. If a visitor clicks on an AdSense advert, the owner of the website where the ad appears makes a share of the money that the advertiser is paying Google for the click.

Google deals with all the tracking of visits to the webmasters pages and clicks on AdSense advertisements, following which it processes payments. As a consequence, anyone who owns a website can show advertisements relevant to the content of that site and also relevant to their visitors' interests without having the administrative nightmare of searching for advertisers, collecting monies due and monitoring statistics.

Google has done a huge amount of work to ensure that advertisers and publishers alike have what they want and need from the AdSense network so the three major reasons why publishers need AdSense are as follows:

1. Appearance

In order that AdSense adverts blend with their websites, webmasters can completely customise the appearance of the advertisements that are shown. They can choose from a large range of sizes and shapes, background and text colours, border colours and corner shapes. There are text ads, video ads and graphical ads too. This in itself has two advantages, the first being that the aesthetics of the website aren't compromised and the second is the attractiveness to the visitor.

2. Tracking

Google offers webmasters the opportunity to create "channels" which generate a code to be included in the script on the webpage. When the channel is created the name given to it by the webmaster will indicate the position of the advertisement, thus the publisher can ascertain whether the placement and appearance of the ad unit is attractive to his visitors, judging by the number of times each one is clicked.

The reporting facility provided by Google can be grouped by date and/or channel and shows click through rates and earnings thus allowing webmasters to tweak the advertisements shown on their site for maximum income.

3. Advertisers

Advertisers appreciate the fact that their advertisements are being shown on relevant websites to a targeted audience. This in turn gives them maximum return for their advertising budget, attracting interested visitors who are likely to purchase. As a consequence, Google will never run out of a source of adverts and as long as your website contains interesting articles or reports, you will always have adverts from the network on show.

So, to summarise, if you have a content-rich website, which receives targeted traffic from the search engines and which you maintain and add to on a regular basis, you would be crazy not to include advertisements from the AdSense network in your pages in order to supplement your income the easy way.