An index is a tool that tracks the combined performance of a selected group of companies, giving a single number that represents how that group is doing as a whole. Instead of following one company, an index reflects the broader direction of a market or sector. Indices are widely followed because they show the “big picture” — whether a market is generally rising or falling. They are influenced by factors like corporate earnings, interest rate decisions, and major economic news. For traders, an index offers a way to engage with overall market movement rather than the fortunes of any single business.