Extents in SQL Server

Extents : 

The page is the fundamental unit of data storage in SQL Server where actual data is present.

An extent is a collection of eight physically contiguous pages.

An extent helps to manage pages efficiently.

            SQL Server supports 2 types of extents                     

                               a.  Uniform Extents     

                               b . Mixed Extents

Uniform Extents: All 8 pages in an extent contains data from same object.

Mixed Extents: All 8 pages in an extent contains data from different objects.