You will encounter 限购 primarily in two major contexts of modern urban life. The rules are often complex and vary by city.
Real Estate (房地产 fángdìchǎn): This is the most common use. A city's 限购 policy might state that:
People without a local `户口 (hùkǒu)` (household registration) cannot buy property at all, or must have paid social security in the city for a certain number of years.
Local residents may be limited to owning only one or two properties per family.
These rules are a constant topic of discussion among anyone considering buying a home.
Automobiles (汽车 qìchē): To combat traffic congestion and air pollution, megacities like Beijing and Shanghai have 限购 policies for new cars. This doesn't just mean you need money; you need a purchase permit.
This permit is often obtained through a `摇号 (yáo hào)`, a lottery system where millions of people enter but only a tiny fraction win the right to buy a car each month.
In some cities, the permit is auctioned to the highest bidder.
The connotation of 限购 is almost always neutral when stated in the news but is felt negatively by the individuals it restricts. It's a bureaucratic hurdle that can dramatically alter a person's life plans.