The AdSense engine at Google sends its bot, called Googlebot, out to visit your site on a regular basis to examine your pages. This bot is simply a program which reads your pages. Google bot looks at your key words, the structure and formatting on your web pages, the native language of your site, etc¼ Using the information gathered by the Googlebot, Google then sends AdSense ads to your site which are the most likely to entice your visitors to click on them. 

The Googlebot will even tell AdSense if your blog is in a language other than English, so that your ads come to you in the language of your site. It wouldn't be very good to see English ads on a Spanish site or vice versa. AdSense is available in many languages and regions around the world. And, the ads you will receive on your blog will be from your own region and in your native language. 

The longer your website is up, and the more you are scanned by the Googlebot, the more tightly matched the ads become to your content. At first the bot might misunderstand the meaning of your blog if you have not done a great job of using lots of relevant keywords. If you have a blog about coffee yet you talk a lot about your children in your blog message posts, then you might end up with ads which would interest readers of a children's blog. If you want to monetize your blog it is important to stay on topic, most of the time, so that the Googlebot reads your blog and serves up the ads which you want to show up on your site. 

Knowing what standards Google is looking for on your website with their Googlebot, and keeping your blog to be compliant with those standards, makes AdSense work it's best for you. For some unknown reason AdSense prefers pages with lots of text and not too many graphics. Googlebot also sees larger or bold text as having more importance than regular text. This means that posting large and bold key words can help AdSense zero in on the subject of your blog better. It also means that you will want to keep the photos and graphics to a minimum and make sure you stay on topic a large percentage of the time. If you want to have a blog with a lot of photos you might consider starting a second blog and hosting them all there and then link the two blogs together. 

One valuable tip for all bloggers is to make sure you start all of your blog posts with a large, bold, title at the beginning of the text section of each blog message post. It is very quick and simple to do this and yet it is very effective with AdSense. If your blog is about frogs and you mention frogs in your title and then again as a bold title at the beginning of your blog message post, the Googlebot can better understand that your blog is about frogs. Taking the time to do this simple thing will insure that the Googlebot understands more quickly 

what your blog is about and serves you up relevant AdSense ads. It also looks natural to your readers and isn't distracting to them. It is also less time consuming than dealing with special tag words or any other search engine games bloggers play. 

Another good tip with AdSense is to make sure you use your topic's keywords often in your blog post titles, and use them again within the content of your posts as well. For example, if you have a blog about chickens you will want to make sure your post titles mention the word "chicken" in them. You will also want to make sure you mention chickens, eggs, and other related words as much as possible within your posted messages. The more you can post relevant titles and content loaded with keywords, the better AdSense will work for you and send you relevant ads. You have a much higher click through rate for ads which are relevant to the topic of your blog. Think about the times you have clicked on the Google AdSense ads on a website you were visiting. Generally speaking, was it for something related to the topic you were already reading about? Of course it was. 

However, all of that being said, you do not want to overload your posted messages with keywords. Your reader wants to know that you publish your blog for them to read, not to make money from them. By posting a sentence which reads; "the chickens in my chicken coop are working on having more chickens in the spring." looks like a sentence I tried to use the word "chicken" in as much as possible. There is definitely a balance to be struck between pleasing your readers and pleasing the Googlebot who serves your AdSense ads on your website. Instead of stuffing in those keywords try making more sentences or using them in the title and adding a bit more text to your message posts. 

You also do not want it to appear that you set-up your blog with a bunch of keywords simply for AdSense. You also do not want to copy content from free sites like wikipedia and then paste them into your blog. These blogs are called splogs (short for spam blogs) and doing this can get you kicked-off of AdSense and Blogger as well. You need a blog with good original content, not just a bunch of keywords. By creating a splog you can get a high search engine ranking temporarily but why would readers want to visit or return to your blog if all it offers them is some keyword garbage and ads to click on? 

It can take a bit of time for the Googlebot to visit your website and determine what its main topic is. If your website is new to AdSense, Google will not guess about your topic, it will simply place ads on your blog for charities or public service announcements as to not waste the advertising dollars of its AdWord clients. This is good for you the blogger as well. The last thing you want to do is to see ads on your blog which have nothing to do with its topic. By putting up the neutral ads Google has solved this problem.