Every Excel spreadsheet contains rows and columns. Most of the time, columns are identified by letters (A, B, C), and rows are identified by numbers (1, 2, 3). In Excel, this is known as the A1 reference style. However, some prefer to use a different method where columns are also identified by numbers. This is known as the R1C1 reference style.
In the example below, the image on the left has a number over each column, which means it is using the R1C1 reference style. The image on the right is using the A1 reference style.
While the R1C1 reference style is helpful for certain situations, you'll probably want to use the A1 reference style most of the time. This tutorial will use the A1 reference style. If you're currently using the R1C1 reference style, you'll need to turn it off.