There are really three broad categories of retirement communities:
Retirement communities are often built in warm climates, and are common in Arizona, California, Florida and Texas but are increasingly being built in and around major cities in cold climates too.
So far 6 U.S. states have created Certified Retirement Community programs with approximately 70 towns and communities included (see list). The obvious purpose of these programs is to encourage economic development - retirement, particularly baby boomer retirement - is very big business. States seek to encourage retirement in their states; keeping existing residents and encouraging out of state residents to move to a new state. Bill Haas of the University of North Carolina's Institute for the Future of Retirement estimates that the economic impact of a retiree household moving to a state is the equivalent of 1.4 factory jobs.
The six states that have publicized their certification programs are: - Texas - Louisiana - Mississippi - Kentucky - West Virginia(West Virginia calls its program a "Designated Retirement Community". -Tennessee has a program that promotes retirement in select communities in that state; the program is called "Retire Tennessee.
A number of publishers have created lists of the 100 best retirement communities or "100 best places (or towns) to retire" . For the most part these lists are helpful in terms of finding desirable communities to live in. One drawback to these lists is that these communities often become more expensive as a result of their popularity.
Notable United States retirement communities / "active adult" communities.
Lauriston Park Village, Cambridge, Waikato owned and operated by Neil Retirement Villages.
In the United Kingdom retirement villages as mentioned above do not really exist. The closest is probably Hartrigg Oaks in York, and other experimental projects led by the Joseph Rowntree Trust.
Retirement homes are very popular as is sheltered housing. Retirement villages do exist (in name anyway) but they rarely exceed 100 residents and are generally composed of independent flats within one building.