Nifty
In short
The Nifty 50 is a stock market index that tracks the performance of the fifty largest and most liquid companies listed on the National Stock Exchange of India.
In plain words
It acts like a thermometer for the Indian economy. When the Nifty goes up, it means the biggest companies in India are generally doing well. If it goes down, those companies are losing value.
A simple example
If you want to know how the Indian stock market is doing without checking every single company, you look at the Nifty. It gives you a quick snapshot of the top players.
Why it matters
Investors use it as a benchmark to see if their own investments are performing well. It is also used to create funds that automatically track the top fifty Indian businesses.
Easy to mix up
Do not confuse it with the Sensex, which tracks the thirty largest companies on the Bombay Stock Exchange instead.