Use Dollar Symbol..
You may not know about Relative Reference and Absolute Reference in Excel but you might heard that "using dollar ($) symbol in excel..". The name of using dollar ($) symbol in reference is nothing but Relative Reference and Absolute Reference.
What is Cell Reference ?
A Cell Reference refers to a cell or a range of cells on a worksheet and can be used in a formula so that Excel can find the values or data that you want that formula to calculate.