In SQL Server, data is stored in tables. Behind the scenes, however, these tables are divided into 8-kilobyte (8 KB) units called pages. Each page is 8,192 bytes in size, and this is a fixed value that cannot be changed.
Out of the 8,192 bytes, the first 96 bytes are reserved for the page header, which stores metadata about the page. This leaves 8,096 bytes for storing rows of data. However, a single row can only use up to 8,060 bytes, as 36 bytes are reserved for additional metadata, such as the slot array, versioning tags, and forwarded record pointers.
Read on for more information about the fundamental unit of storage in SQL Server.