Preheat oven to 225F (105C) and line a large cookie sheet (or two regular-sized cookie sheets) with parchment paper. Set aside.
Combine egg whites, cream of tartar, and salt in a large, completely clean, completely grease-free bowl.
Using an electric mixer or a stand mixer, stir on low speed until mixture becomes foamy.
Increase speed to high.
With mixer on high, gradually add sugar, about 1 Tablespoon at a time, stirring after each addition until sugar is dissolved.
Beat until mixture is thick, shiny, and has increased in volume. Mixture should have stiff peaks and sugar should be completely dissolved.
Stir in vanilla extract and any other extract you may like to use. If using food coloring, add the food coloring at this stage, too.
Fit a large disposable piping bag with a large tip and transfer meringue to prepared piping bag and pipe onto prepared cookie sheet.
Bake on 225F (105C) for 1 hour. Turn off the oven once the baking time has passed, and do not open the oven. Leave the oven door closed and allow cookies to cool completely in the oven (1-2 hours) before removing.
Meringue cookies should be crisp and can be stored in an airtight container.
