What is index meaning?

In general, an index refers to a measure used to track changes to something over time. In finance, an index is a statistical measure used to track the performance of a group of stocks or companies. For example, the Dow Jones Industrial Average is an index that tracks the performance of 30 large publicly traded American companies. In the publishing industry, an index is a list of keywords or topics in a book that helps readers find specific information. In information technology, an index is a database structure that allows for efficient retrieval of data from large collections or databases. In general, an index provides a quick and easy way to navigate or find relevant information within a larger set of data.