An assisted living residence is also sometimes known as an assisted living facility. This kind of care for elderly residents falls somewhere in between the 24 hour a day care that is provided in a skilled nursing facility and a senior retirement community.
In general, the folks who live in assisted living facilities need some help during the day and at night but they do not need or want the kind of personal attentions that comes with being a resident in a nursing home.
In the past couple of decades, the amount of people who are living to retirement age and better has increased tremendously. Not only are there more and more baby boomers as a group, but because of increases in the quality of medical care and increases in the general standard of living, more people are living longer.
In some cases people are living a lot longer. The median life expectancy for people who are retired has increased nearly 5 years across the board just in the last few years. This means a big increase in the number of people who are in need of a place to live when they retire.
Its not that folks can not simply stay in their homes they have lived in for the other parts of their lives, it's that sometimes they need some extra help and care in dealing with the activities of daily living. In some cases, this means they might need help with getting the washing done, or the meals prepared or the apartment cleaned.
In other cases, it means that a nurse has to help with giving the medication that they need. Most of these things are regulated by the states and the different states in the US have different rules about what kind of care is not allowed to be given in an assisted living residence.
In general, if retirees are in need of 24 hour a day care, they need to be in a nursing home type of facility, not an assisted care facility. But some retirement communities are quite large and inclusive and have a policy of aging in place, so that the residents can stay there in that community no matter what kind of care they need.
Baby boomers will soon be retiring in very large numbers and this will add a lot of people into the population of folks who are in need of the care they can get in an assisted living residence. That makes it a very good thing that so many more places are being built to accommodate all the people who need places to live.