Blue chips refer to stocks of very well known companies. While there is no exact definition in terms of revenue or market capitalization, these companies sell widely used products or services, are internationally recognized and are financially stable. Generally, all the stocks in the Dow Jones Industrial Average are considered to be blue chips. Other examples of blue chip stocks include Berkshire Hathaway and Royal Dutch Shell.
Blue chip stocks are generally less volatile than other stocks, and are considered to be "defensive" stocks. Due to their stable profitability, these companies, on average, also last longer. However, it does not mean that blue chip stocks do not fail. For example: Ford and Lehman Brothers were both considered to be blue chip stocks at some point.
The name is derived from the chip color in a poker table (blue being the most valuable chip).