Some web sites have their drop-down list boxes set up in such a way that as soon as you select a different option from the list, you jump to a new page. The BBC’s weather page is a typical example. If you choose a different UK region from the list, you will be immediately transported to the local weather page for that region.
So what do you do if you don’t have a mouse for clicking on the drop-down and making the list options visible? Just pressing the down key on your keyboard changes the selected item in the list, and jumps you to a different page, so that doesn’t work. The answer is Alt+Down Arrow. This expands the list, and allows you to run up and down with the arrow keys without changing the active item. Press Enter once you’ve made your selection, and Bob’s your uncle.
Many, many more keyboard shortcuts are listed on Microsoft’s pages for keyboard assistance.