Linked from
The 7 pages that link to Meringue, each with the reason it gives.
EggBroader topic: Whipped egg whites create the foam structure in meringues.
Egg whiteBroader topic: It is a familiar example of egg-white foam stabilized and then set by heat.
Eggs as foodBroader topic: Egg-white foam supplies meringue’s airy structure.
Egg substituteRelated: Aquafaba can create a similar foam for egg-free meringues.
Potassium bitartrateRelated: Small amounts of cream of tartar help stabilize whipped egg-white foam.