Q:

is a "table page" something like an imaginary row or something?

http://searchsqlserver.techtarget.com/tip/Differences-between-varchar-and-nvarchar-in-SQL-Server:

The size for a table page is 8,196 bytes, and no one row in a table
  can be more than 8,060 characters. This in turn limits the maximum
  size of a VARCHAR to 8,000 bytes.

What exactly is a "table page"? 
is a "table page" something like an imaginary row or something?

A:

See this link for an explanation: Understanding Pages and Extents
Quote:

The fundamental unit of data storage in SQL Server is the page. The
  disk space allocated to a data file (.mdf or .ndf) in a database is
  logically divided into pages numbered contiguously from 0 to n. Disk
  I/O operations are performed at the page level. That is, SQL Server
  reads or writes whole data pages.

Here's another one: SQL Server data structures
Quote:

In SQL Server, data is organized in pages. A page has a fixed size (8
  KB). Each page contains records. The number of records that can be
  stored in a page depends on the size of the records. The operation of
  reading data from a page is called a logical IO. The smaller the size
  of a record is, the more records can be read with the same number of
  logical IOs.

