It stands for homeowners association: the private nonprofit corporation that owns and maintains the shared property in a subdivision or building, enforces the covenants recorded against every lot in it, and bills each owner a share of the cost.
The letters are the easy part. The useful part is what an association actually is, which is a small private government with a budget, an elected board, a set of rules recorded in the county's land records, and the power to put a lien on your home if you do not pay. None of that depends on you agreeing to any of it. It came with the land.
Most of the Las Vegas valley is inside one, because most of the valley was built as master-planned subdivisions after associations became the standard way to build them. General information rather than legal advice.
What the thing actually is
An association is a corporation whose members are the owners of the units inside a defined boundary. It holds title to the common property, or the right to maintain it: private streets, gates, entry landscaping, parks, pools, clubhouses, and in a condominium the building itself. It has articles, bylaws, a board elected by the owners, an annual budget and, usually, a management company doing the day-to-day work.
The document that creates it is a declaration of covenants, conditions and restrictions, recorded in the county land records against every parcel in the community, normally by the developer before the first house was sold. Because it is recorded against the land, it binds whoever owns the land next. That is the sentence to remember: you did not sign the CC&Rs and it makes no difference.
The Nevada definition, and the three shapes it takes
Nevada calls what an association governs a common-interest community: real estate described in a declaration where owning a unit obliges the owner to pay a share of taxes, insurance, maintenance or services for common elements (NRS 116.021). That obligation is the definition. If it exists, the community is one, whatever the neighborhood calls itself.
It comes in three shapes. A planned community is the usual valley subdivision of detached homes where the association owns the space between them. A condominium is a community in which parts are designated for separate ownership and the rest is owned in common by those same owners, which is what makes the roof and the exterior walls the association's problem rather than yours (NRS 116.027). A cooperative is rarer: the association owns all of the real estate and each member has the right to occupy a unit (NRS 116.031). Nevada also still has an older condominium statute on the books (NRS 117.010), which is why a very old building's paperwork may read differently from a new one's.
Membership is automatic, and so is the bill
Buying inside the boundary makes you a member on the day of closing. There is no application, no joining fee, and no opting out; the assessment is allocated to your unit by the declaration, not by whether you use the pool. Selling is the only exit an individual owner controls.
Against that, the association has three powers that a neighbor does not. It can assess, meaning charge you your allocated share of the budget and of any special assessment. It can enforce, meaning fine you for a violation of the recorded covenants and rules after the notice and hearing its documents and state law require. And it can lien: in Nevada an unpaid assessment becomes a lien on the unit, and part of that lien sits ahead of the mortgage, up to charges for a collection notice plus nine months of common-expense assessments based on the periodic budget (NRS 116.3116). That priority is why lenders and title companies care about association balances as much as owners do.
What it means when you are shopping
Three questions answer most of it. What does the association own, because that determines what the dues carry and what you still pay for yourself. What is the assessment, and does a master association bill on top of a sub-association. And how funded are the reserves, because the alternative to a reserve is a special assessment.
In Nevada all of that arrives in one envelope. A seller in a common-interest community must furnish a resale package with the declaration, the rules, the budget, the reserve summary and the balance owed on the unit, and the buyer may cancel by written notice until midnight of the fifth calendar day after receiving it (NRS 116.4109). It is the most useful document in a Nevada purchase and the most commonly skimmed.
Questions people ask
Is an HOA a government?
No. It is a private nonprofit corporation created by a recorded declaration, governed by a board the owners elect, and regulated by state statute. It has no police power, but it can assess, fine and place a lien on a unit, which is more power than most private organizations hold.
What is the difference between an HOA and a condo association?
Mostly what is owned. In a condominium the association owns the building and the land in common, so roofs, exteriors and shared systems are its responsibility. In a planned community of detached homes, each owner keeps their own house and lot and the association owns what is between them.
Does every neighborhood have an HOA?
No. Older neighborhoods often have none, and some have a voluntary association with no recorded declaration, no assessment power and no lien. The definitive check is whether a declaration is recorded in the chain of title for that parcel.