There are several situations where you may want to select multiple files at the same time (for example when attaching documents or photos to an email, or moving them from one folder to another on your PC). You can do this quickly and easily using your keyboard in conjunction with your mouse/trackpad.
Using Control / Command to select
On a PC you can hold the Ctrl (control) key and click on each item (using your mouse/trackpad) to select multiple items simultaneously. This is a useful technique for copying, moving or attaching multiple documents to an email in one easy step. The equivalent of this process on a Mac is to hold the Command key
In this example I first selected file 1. I then proceeded to hold down the ctrl / command key while I then clicked on file 3, file 5, file 6 and file 7.
Using shift to select
You can also select a range of items using the Shift key. To do this you must first click on the item that will define the beginning of the range you intend to select.
After selecting the first item in the range you can then hold the shift key and click on the last item in your intended range to select all the items. (In this case I shift clicked on file 10)
These two methods can be used in conjunction with each other to make complex selections easily and efficiently. For example, one could select a range of items using the shift selection method then deselect only certain items using control (ctrl) / command click.