Starter shingles are, as their name imply's, the starting shingles of a Roof System. They are installed on top of the Drip Edge/Rake Edge and on top of the Leak Barriers and begin the overlapping pattern for the remainder of Shingles on the roof.
Simply put: One single row of starter shingles is installed everywhere your roof ends, ie: in the same areas as with Drip Edge and Rake Edge.
As with every other part of a Roof System, different types of starter shingles are offered by many different manufacturers. Fortunately for you, you don't need to select what type of starter shingle to use on your roof, because the manufacturer of the Field Shingle you chose chooses for you. As long as your Calgary roofing contractor follows the manufacturers recommendations when selecting starter shingles, you're in good hands.
A note of interest: starter shingles set the beginning pace for the rest of the Shingles on your roof. If the starter shingles are installed straight, then the installation technician will be off to a good start. Also, starter shingles need installed 6" off set from the remaining Shingles on your Roof System.
Another easy aspect for you about starter shingles is some manufacturers produce starter shingles which can be used with the Field Shingles of their competitors. Not all starter shingles however are interchangeable. To avoid any 'unpleasantness', double check with your roofing contractor that they will be installing a proper starter shingle.