Pay per click (PPC) advertising offers the option of displaying ads on search network as well as on content network. The content network displays ads on websites -- blogs, ezines, online newspapers, and more -- that contain content relevant to the PPC ads, while search network display ads on search engines as the term suggests.

The content network reaches more people compared to search network. However, it’s seen that the quality of traffic is not high. Since PPC ads displayed on content network reaches a broad range of audience, it’s neither targeted nor can be very relevant. For example, to a person reading a blog, the ads displayed there may not have much relevance. If he or she clicks on the ads, it may be usually due to curiosity but with no intention of purchasing or signing-up for something. Thus, traffic generated via content network may be large but quality wise poor.

The search network only displays ads when someone uses a relevant search term, also called keyword, to find information about a product or service, or something else. The person here is actually looking for information and is really interested in the product or service. Thus, the traffic here may be less but it is quality traffic that may generate ROI.

Many advertisers activate both search network and content network in their PPC interface to display ads and divide their budget between the two -- often search network getting a bigger portion of the budget. There are many who find content network to be a futile exercise and waste of time and money, and just concentrate on search network.

Google now calls its content network, display network. Rather than specific search term, text, image, video or rich media ads are targeted based on themes in the keyword list. It allows the advertisers to target sites that have teamed-up with Google, YouTube, and more.