What is the "Google Search Network" data in the Google Adwords Keyword Tool?

[webtraffic1]

What is the "Google Search Network" data in the Google Adwords Keyword Tool?

When I do a keyword search on the Google Adwords Keyword Tool there's a field called "Google Search Network".

The data is different from the global and local monthly searches. What is the Google Search Network data?

For example, I search for "Chicago Jobs" and the local exact is 14,800, but the Google Search Network is 40,500.

 

[Nebraska]

"The Search Network is comprised of Google Search and search partners' sites.

The Search Network includes Google Maps, Google Product Search, and Google Groups along with entities such as Virgin Media and Amazon.com" -- From Google's website.

Essentially, it is a network of many sites.