If you have the need to format several rows or several columns the exact same way, it can be tedious to make the exact same adjustments on each row or column. Excel offers a better way.
Reach back to your Word Processing days for the idea. If you wanted to change the font for every word in a paragraph, you first "Selected" the paragraph and then you changed the font. It would have been silly to select each letter one at a time and change the font. Similarly, if you want to format several rows or columns exactly the same, you should select the "target" and apply the format. The question to answer is..."How do I select more than one row or column at a time?"
Suppose
you wish to widen the columns D, E, and F the exact same amount. You could
make adjustments in each column one at a time. This would be tedious and
perhaps even difficult.
If you carefully move your mouse over the column heading D, the mouse changes to a down arrow. If you click, you select all of the cells in column D.
Now if you keep the mouse button depressed and drag the mouse pointer over Column E, you will select both Column D and Column E.
If
you continue to depress the mouse button and drag the pointer over Column
F, you will select Columns D, E, and F.
With all three columns selected, your "target" is selected. If you now adjust the column width of any one of these columns, the adjustment will be applied to all columns that were selected!
Note that the columns are all the same width. You know this is true because the width adjustment made to one column will be applied to each of the columns in your target selection group. Much less work for you!
Similarly, if you want to apply a format to all of the cells in a single row, you would click on the number of the row.
If that same format is needed on several other rows, you would drag the mouse up or down from the initially selected row to select multiple rows. Whatever format feature that is selected will be applied to all of the cells in the selected rows.