If you have seen the $ signs used in an Excel formula or function you might have wondered what they are for. You might also have been looking for something that stops cells or ranges in formulas or functions from changing. What we are looking at here is using absolute referencing instead of relative referencing. If you are using a combination of the two it is called mixed referencing.
See this video tutorial to see how to use the $ signs.
Gary Schwartz's Blog 