The Sensex, short for "Sensitive Index," is the flagship stock market index of the Bombay Stock Exchange (BSE) in India. It is a market capitalization-weighted index that represents the performance of the 30 largest and most actively traded companies listed on the BSE. The companies included in the Sensex are representative of various sectors of the Indian economy, providing investors with a broad overview of the stock market's health and direction.

The Sensex serves as a barometer of the Indian stock market's overall performance and investor sentiment. It measures the collective movement of the constituent stocks and reflects changes in their prices over time. The index is calculated using a base value, which is adjusted periodically to account for corporate actions like stock splits, bonuses, and mergers.

Investors and analysts closely monitor the Sensex to gauge the market's performance, identify trends, and make informed investment decisions. When the Sensex rises, it indicates an overall positive sentiment in the market and vice versa.

The Sensex has a significant impact on investor confidence and the Indian economy as a whole. A rising Sensex can boost investor confidence and attract foreign investments, while a falling Sensex may cause concern and lead to market corrections.

In addition to the Sensex, India also has another major stock market index called Nifty 50, which is managed by the National Stock Exchange (NSE) and represents the performance of the 50 largest and most liquid Indian companies.

Overall, the Sensex is a vital tool for investors, policymakers, and analysts, providing valuable insights into the Indian stock market's performance and trends.