A retirement community is a residential community or housing complex designed for older adults who are generally able to care for themselves. Assistance from home care agencies is allowed in some communities, and activities and socialization opportunities are often provided. Some of the characteristics typically are: the community must be age-restricted or age-qualified, residents must be partially or fully retired, and the community offers shared services or amenities.

There are various types of retirement communities older adults can choose from, and new types of retirement communities are being developed as the population ages. Examples of retirement community types include:

Retirement communities are often built in warm climates, and are common in Alabama, Arizona, California, Florida, Georgia, Hawaii, Louisiana, Mississippi, Nevada, and Texas, but they are increasingly being built in and around major cities throughout the United States. The oldest known and longest continuously running retirement community in the United States is Ryderwood, Washington. Ryderwood was originally established in 1923 as a Long-Bell logging camp, then was sold to Senior Estates, Inc. in 1953 to create a retirement community. Senior Estates, Inc. converted the town into a retirement community. Time Magazine covered the event in the real estate section with the article "Old Folks at Home". As of 2019, Ryderwood remains a retirement community. Del Webb opened Sun City, Arizona, with the active adult concept, in 1960. In 2011, The Villages, Florida became the largest of these communities. While new retirement communities have developed in various areas of the United States, they are largely marketed to older adults who are financially secure. Lower income retirement communities are rare except for government subsidized housing, which neglects a large proportion of older adults who have fewer financial resources.

Retirement communities have been around since the 1920s and 1930s.

Continuing care retirement community (CCRC) is the primary term for a major part of the retirement scene, in books, magazines, accreditation and legislation. A typical definition, from a New York Department of Health website is "Continuing care retirement communities (CCRCs) and fee-for-service continuing care retirement communities (FFSCCRCs) are residential alternatives for adults that offer, under one contract, an independent living unit (an apartment or cottage), residential amenities and access to a continuum of long-term care services, as residents' health and social needs change over time." The accrediting agency CCRC/CARF uses the term CCRC with the same meaning.

In 2010, over 2,000 CCRCs existed in the United States with an estimated 640,000 residents. The popularity of CCRCs is increasing, as the number of older adults in such retirement communities has more than doubled during the last decade. The primary benefit of the CCRC model is that it allows people to age in one community and receive additional healthcare services if needed. Additionally, CCRCs embody a general sense of community and offer peace of mind for couples with the assurance that they will always be near each other, even if one spouse needs more care.

There are three levels of care in most CCRCs and when residents' health needs increase, they will transition from one level to the next. The levels are:

Most CCRCs include an entrance fee and a monthly fee, and these costs vary widely depending on several factors: the luxuriousness of the facility, the size and type of housing unit, whether the person enters alone or with a spouse, and how much future care is covered (this could be through insurance, government plans, or out of pocket). Fees tend to be expensive and usually do not include additional services such as phone and television. Additionally, residents should plan on a 3-6% increase in monthly fees each year.