Next in turn point to the data to answer any given request. Indexes Indexes are SQL Server's internal method of organizing the data in a table in such a way that it can be retrieved optimally . Optimal in this case refers to the quickest way. Indexes are collections of unique values in a given table and their corresponding list of pointers to the pages of data where those values are physically represented in a table. At a high level indexes are a shorthand way of the database recording information that it's storing in tables.
Indexes are just another kind of object in the database and have storage needs like tables.
Just as tables require pages of data to store their rows in indexes require pages to store their summary data in. This allows the server to scan a list of index pages before choosing to scan the whole table looking for matching data. Working with Indexes is a test and test again proposition. You're faced with many different variables that you'll need to weigh against one another in terms of performance and the end-user experience. For example the indexes you create will generally be driven by the data-retrieval habits of the applications on the system.