Adverse possession transfers title to someone who has possessed land belonging to another for the statutory period, in the manner the law requires. It sounds startling and is genuinely rare, because every element must be satisfied continuously.
The elements, which vary in wording by state, generally require possession that is actual, open and notorious, exclusive, hostile or adverse to the true owner, and continuous for the statutory period. Some states add a requirement of paying property taxes, which sharply reduces successful claims.
Hostile does not mean ill-willed. It means without the owner’s permission. Permission defeats the claim entirely, which is why a licence granted in writing is the standard defensive response to a neighbour’s encroachment.
Tacking. Successive possessors in privity may add their periods together, which is how claims mature across changes of ownership.
Where it actually arises. Not in dramatic land grabs but in boundary disputes: a fence built in the wrong place decades ago, a driveway that crosses the line, a garage corner over the boundary. The remedy sought is often a prescriptive easement rather than title.
Practical guidance for owners. A survey at purchase, and attention to encroachments when they appear. Granting written permission stops the clock; ignoring an encroachment for years does not.