A stock market index is an objectively important figure. It offers a broad representation of what's happening in the stock market. The idea is to take the biggest, most influential companies from multiple industries and track their performance each day. Nifty 50 happens to include 50 stocks that do this job. There's also the Sensex 30. But no matter which way you swing, you have to remember that they both do the same thing. They're a benchmark, a barometer to give you the market's pulse.