Absolute Reference in Excel

Referenced from:http://ulearnoffice.com/excel/copy-paste.htm

By copying a formula, the relative reference changes too. The column reference changes when you copy a formula horizontaly (left to right). The line reference changes when you copy a formula verticaly (up and down).

You can use the dollar sign ($) to "fix" or "freeze" a column or a line in a formula. When the formula will be copied, the parts that are frozen will not change. To freeze, you must place the dollar sign ($) in front of the column or line position.

A1	Neither the column nor the line is frozen.
$A1	The column is frozen but not the line.
A$1	The line is frozen but not the column.
$A$1	The line and the column are frozen.