In many folders you can select multiple items, to perform operations on them (ex. select multiple emails to delete, etc.).
To select an item, click on the check box that is in the same row of the item.
You can click multiple check boxes to select multiple items.
To select all items: click on the 'Toggle' icon that is at the top of the column where all the checkboxes are.
The icon looks like this:
. Clicking again on this
icon will unselect the selected items. Note: this icon selects/deselects
all the items in the current page. There may be more items in successive
pages. Consider changing the number
of lines displayed per page.