Value investing is an investment strategy that involves picking stocks that appear to be trading for less than their intrinsic or book value. Value investors actively ferret out stocks they think the stock market is underestimating. They believe the market overreacts to good and bad news, resulting in stock price movements that do not correspond to a company's long-term fundamentals. The overreaction offers an opportunity to profit by buying stocks at discounted prices—on sale.
The basic concept behind everyday value investing is straightforward: If you know the true value of something, you can save a lot of money when you buy it on sale. Most folks would agree that whether you buy a new TV on sale, or at full price, you’re getting the same TV with the same screen size and picture quality.
Stocks work in a similar manner, meaning the company’s stock price can change even when the company’s value or valuation has remained the same.
Stocks, like TVs, go through periods of higher and lower demand leading to price fluctuations but that doesn't change what you’re getting for your money.