Google's AdSense seems to be the most popular system of advertising in blogs. This free service for web-publishers is easy to use, especially as ads are contextual (they change depending on the content of a particular page to display relevant ads for your readers). Most bloggers are eligible to sign up for AdSense, which you can do using this link.
Ensure you are aware of Google's policies for AdSense publishers, including sites which are prohibited from featuring AdSense, site and ad behaviour, and the number of ads allowed in a page.
How many ads can be displayed in a single page?
In any single web page, you can have:
- Up to three ad units
- Two AdSense for search boxes
- Up to three link units
- A maximum of three referral units
These regulations can be especially important for bloggers who choose to include ads in their posts, since the main page of your blog can feature a number of posts, and you cannot feature ad units in all of them. However, there are methods of displaying ads in posts only on post pages, as I will explain in a later installment.
How does Google decide which ads to display?
Keywords from your title and blog posts are used to determine the most relevant ads to display. It's best to try and keep each blog post on one particular subject and include relevant keywords in the title and at least a few times in the article itself. Problogger features some great advice on ensuring relevant ads are displayed on your site.
How do I place ads in my blog?
Blogger now has widgets you can use to include AdSense in your sidebar. You can configure the colour schemes and size of these ads to suit those of your blog.
Alternatively, log in to your AdSense control panel and click on the "AdSense setup" tab at the top of the page. You can then choose the type of ad you wish to use and get the relevant code, which you should then paste into your template where you would like the ad to be displayed.