When you setup a Google adwords account, your ads are automatically ‘opted in’ to run on the entire Google Network.
Search Total and Content Total, which appear in your Campaign Summary and Report Center reports, represent the two types of sites where your ads can be displayed within the Google network.
Search Total shows the impressions your ad has received from search results pages generated by Google and by Google Network search partners. On these sites, your ads are displayed alongside the results from searches matching your keywords. (If you opt out of Google Network search sites, then the Search Total numbers will reflect results only from searches generated by Google.)
Content Total shows the impressions that your ad receives on content sites or products in the Google Network. On these sites, your ads are displayed alongside content relevant to your keywords. Your ads may appear on news sites, personal web pages, emails or many other types of content sites and products.
See examples of where your ads may appear on the Google Network. You can opt out of the Google Network at any time by editing your distribution preferences.
You can get more exposure by leaving them as they are but sometimes you might want to turn off the content part.
Ive just always thought there’s more chance for click fraud and sometimes the cost per click is higher, which doesn’t seem right, plus you never know exactly where the ads are showing. Sometimes though you want as much traffic as possible and this does give you more exposure.