The controversial porn domain .xxx went on sale Tuesday, despite a lawsuit by two adult entertainment industry giants.

The idea of setting aside an Internet domain for adult material has been debated for more than a decade. In 2000 and 2004, proposals were submitted to the Internet Corporation for Assigned Names and Numbers but garnered widespread opposition from conservative groups. After ICANN initially approved the domain in 2005, .xxx faced six years of legal and procedural hurdles before getting the final go-ahead in March 2011.

The ICM Registry, which will administer the new domain, touts it as a safer and more distinct alternative to traditional domains such as .com. The ICM Registry says creating a .xxx domain is better for those who want to avoid porn, since it provides an easy way to filter out adult entertainment sites. The Internet is home to a wealth of content, suitable for a wide range of ages and values, states the registry's Web site.

The new .xxx sites will be tagged in a way that will make it easy for parents, employers or others to block them from their networks. Some 250 million pages of content have already been labelled under the new system, but at least two major players in the porn industry, Manwin Industries and Digital Playground, have launched a lawsuit against ICM and ICANN. They argue the domain is anti-competitive, charging $60 annually for each domain, a price it says is 10 times of what other top level domains charge.

The proliferation of .xxx addresses doesn't mean porn will disappear from .com sites. Adult sites that buy a .xxx domain are free to keep their .com or other current URL as well.

Many conservative groups suggest that creating a top-level domain for porn is tantamount to an endorsement of it. At the same time, .xxx domains provide better protection than other porn sites, and that benefits people who want access to adult material.

Lawsuit Lawsuit