Alternative Root Server
Alternative Root Servers or the Alternative Domain Servers provides users with alternative gTLDs not currently available in ICANN space. The control of the official Internet is mostly in the hands of the Internet Corporation for Assigned Names and Numbers (ICANN) which is a government-sanctioned private organization of the United States. IANA, a department of ICANN has full control over the ‘root’ server, which is a file on a computer that is kept at Herndon, Virginia. This file works as the official list of domain names on the Internet. 
How do the Alternative Root Servers operate?
Alternative root servers operate by providing users with an alternative root that provides access to gTLDs. In addition, some altroots incorporate the ICANN root, thereby providing access to both the alternative root namespace as well as ICANN's namespace.
History of Alternative Root Servers
The Alternative Root Servers have been in existence since the year 1995. It came into existence when several groups of Internet users found out that they didn’t have any choices other than the .com, .org and so on. The regulation of the Alternative Root Servers was handed to the Internet Corporation for Assigned Names and Numbers (ICANN). In the year 2001, ICANN came up with seven new Top level Domains or TLDs.
The number of Alternative Root Servers in existence
Currently, there are 15 Alternative Root Servers in existence. The operators of these servers range from the non-commercial collectives such as the OpenNIC or the outlawed libertarian free marketers. Of these, the Name.Space co-operates with the two shared alternative root networks which are known as the PacificRoot and the Open Root Server Confederation or the ORSC. The data doesn’t come easily on the alternate namespaces. There is also a lot of difficulty on the use of data of alternate namespaces as it is far from being conclusive. The number of people using the Alternative Root Servers ranges from 5% - 30%. In technical terms, there is no set limit for the amount of TLDs that can operate simultaneously.
ICANN Position Concerning Alternative Roots
ICANN confirms its opposition to alternative roots in "ICP-3: A Unique, Authoritative Root for the DNS" . This document incorporates, by reference, "RFC2826: IAB Technical Comment on the Unique DNS Root" .