American cheese is just mild cheddar and colby jack, with an emulsifier added to help it blend together and melt smoothly. You can literally make bootleg American cheese by shredding the two together, adding an emulsifier (like sodium citrate) and heating until they melt.
That same emulsifier is what makes it so good for burgers. Aged cheddar tends to melt into clumps, and tends to get greasy as the milk fat separates out of the solids. The emulsifier helps the cheese solids and oils stay together, making it less clumpy and greasy.
ThunderclapSasquatch@startrek.website 4 hours ago
American cheese is made from cheddar