Net Neutrality is the principal that all pages on the internet should be treating equally by broadband networks. Google, a strong advocate for Net Neutrality defines this concept more broadly as "the principle that Internet users should be in control of what content they view and what applications they use on the Internet.".
The Politics of Net Neutrality
Net Neutrality is a complicated political issue as lawmakers have struggled with how to classify the internet into different legal frameworks and various interest groups such as the telecommunications companies and consumer advocacy groups have had large stakes in this issue. Net Neutrality became a sound bite issue in 2006 when, Republican Senator Ted Stevens described the internet as "A series of tubes" in an effort to argue against net neutrality. 
Currently, this is still very much a contentious issue with the Senate set to debate this issue later this year. 
Significance in terms of Media Technology and Cultural Change
The future of Net Neutrality will be very important in determining the future of the internet and information technology more generally. If corporations and other powerful entities are able to pay for more bandwidth, the Networked public sphere and the Network economy described by Yochai Benkler in The Wealth of Networks will be threatened. As Benkler implies in his book, eliminating Net Neutrality would have huge negative consequences politically and culturally.