If you're copying cell content to adjacent cells, you can click and drag the
fill handle
(the small square in the lower-right corner of the selected cell). However, with larger spreadsheets this can be awkward because you'll have to hold down your mouse button and wait for Excel to scroll to the bottom of your sheet. Luckily, there's a shortcut: Simply
double-click
the fill handle, and it will instantly copy the cell content down.
Watch the video below to see this shortcut in action.