Preheat oven to 200ºF (93ºC). Line two rimmed baking sheets with parchment paper and set aside. Fit a piping bag with desired piping tip; set aside.

In the bowl of a stand mixer fitted with the whisk attachment or using a hand mixer and a large bowl, begin whipping egg whites at low speed until whites look wet and frothy, about 1 minute. With the mixer running, add cream of tartar and salt and mix until dissolved, about 10 seconds.

Keeping the mixer at low speed, slowly add ¼ of the sugar in a steady stream. Increase speed to medium and slowly add remaining sugar. Continue mixing at medium speed until meringue is thick and glossy and holds firm peaks when you lift the whisk, about 10 minutes. (While you could speed the mixer up for a faster meringue, the meringue is more stable when mixed for a longer time at slower speeds, making it less likely to deflate. The exact mixing time will depend on your mixer and other variables, so keep mixing to reach firm peaks even if longer than the estimated 10 minutes.)

Using a flexible spatula, gently scrape meringue into prepared piping bag. Pipe meringue onto prepared baking sheets.

Bake meringues until dry, about 2 hours. When meringues are done, turn oven off, and allow meringues to gradually cool in the oven for 30 minutes. Slowly crack oven door open, using a wooden spoon to keep the oven door slightly ajar. Allow meringue to cool completely, about another 30 minutes.