ISP forms the backbone of the Internet as they provide services for accessing, using and participating it. Though they have a great power on controlling what content should their users access, it is easily by-passable by changing Domain Name Server (DNS) or using Virtual Private Network (VPN)#.
There is a hierarchy for ISP: Tier 1 (the highest), Tier 2 and Tier 3 (the lowest). Tier 1 ISPs, such as AT&T, and NTT, provides free of charge traffic exchange between Tier 1 networks. Tier 2 ISPs usually provide regional Internet services to the users, for example Telekom Malaysia (TM). Tier 3 ISPs, for instance, Unifi, Maxis, Celcom etc., provide local Internet services. Network traffic that is destined for Tier 2 and/or Tier 3 doesn’t need to travel to a central point for distribution, therefore increase the scalability# of the Internet.