A place usually somewhere near
downtown of a
city, where
Chinese people gather and open
shops to sell
wares from back
home. These
goods they sell are usually unattainable in regular
shops. They include
food,
video rentals and
dry goods.
Many Chinese still live in Chinatown. The reason many Chinatowns are so close to downtown is because when the Chinese first arrived at a city they are poor and settle in the cheapest parts of town. For example, in Toronto Chinatown is close to the University of Toronto, a decent but still poor area, in New York City it is located in lower Manhattan, and in Sydney it is between George Street and Darling Harbor, a fairly decent area.
In cities nowadays with very large Chinese populations, such as Toronto and Houston (I have never been to San Francisco so I can't write about their famous Chinatown), there are several Chinatowns spread all over the city, usually in the suburbs. Those are usually much cleaner and more modern than old Chinatowns. The old ones are usually filthy. Examples: Vancouver, New York City.
Chinatown does not have to be all Chinese, there are many other Asian ethnicities that open up shop there, including Indonesians, Koreans, Japanese and Vietnamese.
Recommended purchases at any Chinatown are the wide range of roasted poultry. You can tell where to get these if you look for a storefront with a giant glass window and rows and rows of roasted birds hanging on iron hooks. Duck and goose are the best. Also, the roasted pork isn't too bad either.
If you're Chinese and you don't know how to speak Chinese, you might be looked down upon in Chinatown. To them, you are a banana. Yellow on the outside, white inside. Not very nice, but oh well, if you're Chinese then you should have at least some knowledge of your own language. Just my opinion.