Aji-No-Moto - 5th Flavor - Umami
MSG gets a bad wrap. When I was younger there was a rumor that is was used as the main ingredient in embalming fluid. While technically it's a Japanese ingredient it's known for it's use in Chinese restaurants.
MSG, stands for monosodium glutamate and it is the sodium of the amino, glutamic acid. Glutamic acid sounds like some sort of leg muscle burn but it's a common amino acid found in foods like mushrooms and tomatoes.
Over 100 years ago a Japanese scientist isolated glutamic acid in foods. Kikunae Ikeda was a Tokyo chemistry professor but he was also interested in how certain foods were so satiating. He studied traditional Japanese broth called dashi and his investigations not only give us Aji-No-Moto, crytsalized MSG but the concept of the 5th flavor via his descriptive term "UMAMI".
MSG is what we now use as a reference for umami quality. It's a specific savory flavor and if using in your kitchen don't be scared. It's as handy to have some in your larder as soy sauce or miso are and once you slip some into a soup you may never return to simply sugar or salt.