Add egg whites, sugar, water, cream of tartar, and salt to a bowl and beat with a hand mixer for approx. 30 sec.
Set the bowl over a pot of simmering water, making sure that the water doesn’t touch the bowl. Beat on high for approx. 5 min., until glossy and fluffy.
Remove bowl from heat, add vanilla extract, and beat for approx. 2 min. more. Let the frosting cool to room temperature and use for cakes, cupcakes, and more! Enjoy!