Take a look at the "The difference between relative and absolute
references" topic in the "About cell and range references" topic in XL
Help.

Essentially,

When copying/dragging/filling formulas, putting a $ in front of the
column character(s) preserves that column in the copied cells. Likewise
a $ in front of the row number.

Put these formulae in the indicated cells:

B1: =$A1
C1: =A$1
D1: =$A$1

Now select B1:D1, grab the fill handle (lower right corner of D1) and
drag down a few rows. Look at how the formula changes in rows 2 and
greater.

Now put these formulae in the indicated cells:

A2: =$A1
A3: =A$1
A4: =$A$1

Select A2:A4 and drag to the right. See how the formulae change.

In article ,
"Richard" <nomailplease.com wrote:

I don't understand why we use cell referencing at all. Can anybody tell me
what is the different between these references $A1, A$1, and $A$1 or exactly
what they do.

Thanks