The BSE Sensex, or Bombay Stock Exchange Sensitive Index, is a stock market index that tracks the performance of 30 large and well-established companies listed on the BSE. It serves as a benchmark for the Indian stock market, reflecting the overall economic health and investor sentiment in the country. The Sensex is calculated using a free-float market capitalization method, which means it considers only the shares available for trading. Changes in the index indicate how the stock prices of these companies are performing, making it a key indicator for investors and analysts monitoring the Indian economy.