My answer on Quora:
A market is for anything that has someone who wants something and someone who provides it. Or, where a transaction takes place.
A stock market is where people buy (want) and sell (provide) stocks. Stocks are bought and sold in different “exchanges”, like the New York Stock Exchange, Nasdaq, or the Bombay Stock Exchange. When people refer to “the stock market” at large, they are referring generally to wherever stocks are bought and sold.
The used car market is where people buy and sell used cars. You may have a used car dealer, or several, in your town. When people refer to this market, they are referring in general to wherever used cars are bought and sold.
The job market is where people apply for (want) and offer (provide) jobs. This may not be a physical location, but a “market” doesn’t need to have a single location, depending on what is being exchanged or transacted.
Same for electronics, food, insurance, even marriage (people “shopping” for the right partner). Clearly, one can get creative.
Beyond having a hypothetical buyer and seller in a market, there can be other market participants. Intermediaries exist in many markets to link buyers and sellers. They often help facilitate how efficient a market can be, and can wield significant market power in the process. Banks are a prime example of intermediaries in the market for money (broadly speaking), where savers save and borrowers borrow.
Quora is an example of an intermediary in the market for information. Providers of information (answers) meet seekers of information (questions) here, on this platform.