A more thorough explanation:

The National Daily Quotation Service, also known as the Pink Sheet, is a daily publication that lists over-the-counter stocks, their market-makers, and their prices. It is printed on pink paper and published by the National Quotation Bureau, a private company.

For example, if you wanted to know the current price of a certain over-the-counter stock, you could look it up in the Pink Sheet. The Pink Sheet would tell you the name of the stock, who is selling it, and how much it is currently worth.

The National Daily Quotation Service is important for investors who are interested in buying or selling over-the-counter stocks. It provides them with up-to-date information on the prices of these stocks, which can help them make informed decisions about their investments.