In a formula in a spreadsheet program, a reference to the contents of a cell that is adjusted by the program when one copies the formula to another cell or range of cells. To understand what happens when one copies a relative cell reference, it is important to know how a spreadsheet program actually records a cell reference.
If one were to type the formula @SUM(C6:C8) in cell CIO, the program would record a code that means, “Add all the values in the cells positioned in the second, third, and fourth rows up from the current cell.” When the user copies this formula to the next four cells to the right (D10:G10), it still reads, “Add all the values in the cells positioned in the second, third, and fourth rows up from the current cell,” and sums each column correctly. See absolute cell reference, mixed cell reference.