Entering data into a spreadsheet is the starting point for any analysis. While you can type the data you need in manually, forms allow you (or in some cases, others) to quickly enter information line-by-line without much of a fuss.
The Form button has been somewhat coyly hidden in Excel 2013, but you can get it back like so:
Right-click anywhere on the ribbon interface, and select "Customize the Ribbon."
In the right-hand pane, choose a section of the Ribbon to add the Forms button to.
On the left-hand side, choose "Commands Not in the Ribbon" from the drop down.
In the box below, select "Form…" from the list and click "Add" to place it in the ribbon.
Now that you have the Form button in your ribbon, you can create a data entry form. Start by creating the headers and first row of entries. Once you have your initial set of data in, you can enter in additional rows with the form command. Simply place your cursor in the top-left corner of your data set and click the form button.