This direct method. Google AdSense is the most popular option in this category, but there are others. Basically you need to register with the network and paste some code snippets on your site. This network will serve contextual ads (either text or images) relevant to your website, and you will earn a certain amount of money for each click.
Profitability of PPC advertising depends on the total levels of the web site and, most importantly, Click-through rate (CTR) and cost per click (CPC). The CTR depends on the design of the site. Ads placed abode fold or blended with content, for example, tend to receive higher CTRs. CPC, on the other hand, depends on the NICE website. Mortgages, financial products, and higher education are examples of profitable niches (clicks worth a few dollars are not rare), while technology-related topics tend to receive lower cost-per-click (sometimes only a few cents per click).
The source of traffic can also affect the overall CTR rate. Organic traffic (the one that comes from search engines) are usually well because these visitors were already looking for something, and they tend to click on ads more often. Social movements of the mass media, on the other hand, is very low CTRs because these visitors tech-savvy, and they just ignore ads.
List of popular CPC advertising networks:
* Google Adsense
* Yahoo! Publisher Network (YPN)
* BidVertiser
* Chitika
* Clicksor