The grades of maple syrup are based on the color and flavor of the product. There are different grading systems in Canada and the United States. They correspond roughly to the time during the harvest season in which the syrup was made, with lighter varieties made earlier than darker grades.
All grades of maple syrup are made from boiling the sap of maple trees. If the syrup is made by other means or has artificial maple flavoring, it cannot be labeled as maple syrup. Maple sap is harvested mainly in February through April. Vermont in the US and Quebec in Canada are the biggest producers of maple syrup.
In Canada, there are three grades of maple syrup: #1, #2, and #3. Canada #1 includes Extra Light, Light, and Medium syrups, all of which can be used on their own. Extra Light, or AA, syrup is best for making candy or for pouring over pancakes and waffles. Light syrup (A) can be used to top heartier treats like French toast and cornbread. Medium syrup (B) can also be used on its own, as well as for glazing or sweetening.
Canada #2 maple syrup, also called Amber or C, is recommended for baking or flavoring. Canada #3 syrup, called Dark or D, is restricted to commercial use.
In the United States, Grade A and Grade B are the main grades of maple syrup. Grade C also exists, but is only used commercially. US Grade A is subdivided into three grades of maple syrup: Grade A Light Amber or Fancy, Grade A Medium Amber, and Grade A Dark Amber. They are all lighter in flavor and color than US Grade B.
Vermont has its own classifications of maple syrup, Vermont Fancy and Vermont Grade A Medium Amber. These are similar in taste and color to US Grade A Light Amber and Grade A Medium Amber respectively, but maintain a higher standard of density and are therefore somewhat thicker products.
In both Canada and the United States, the lighter the syrup, the more delicate the flavor. As the maple syrup season progresses, off flavors become more common and the general flavor of the syrup becomes stronger. Late-season syrups are reserved for baking and should not be eaten on their own.