When working in a large spreadsheet it’s helpful to keep the headings for your columns and/or rows visible as you move around the worksheet.  When you click on the View tab in the ribbon you will see a Freeze Panes button.  Click it and you’ll have three choices.  The first is the most flexible of the three.  When you choose Freeze Panes, the rows above and to the left of the currently selected cell will be frozen to act as headings.  They will stay on screen no matter how far you move down or to the right. So if you want rows 1 and 2 frozen as column headings and column A frozen for row headings, you would click on cell B3, then choose Freeze Panes.  You will see black lines appear showing you which rows and columns are frozen.

The other two options, Freeze Top Row and Freeze First Column, do exactly what they say.  So you can quickly freeze one or the other without worrying about the position of your cursor.  Choosing either of these options will remove any previous settings and apply your new choice.  So if you want to freeze both columns and rows, you must use the Freeze Panes option.

It’s important to note that all three options will be applied relative to what is currently on screen.  For example if row 20 is the first visible row and you choose Freeze Top Row, row 20 will be frozen, not row 1.  As a result you will not be able to scroll above row 20.

To turn Freeze Panes off, simply go back to the Freeze Panes button on the View tab and choose Unfreeze Panes.