ELI5 MSG - how does it make food tasty?

Why does MSG have a bad reputation? What is Monosodium Glutamate? How does it make everything taste delicious? What is umami taste? Is MSG really unhealthy for you, or is that a myth?   ... We explain like i'm five!   Thank you to the r/explainlikeimfive community as always and in particular the following users whose questions and comments formed the basis of this discussion: dude_meister, asquier, therealbiglou, rkwan095, wormsblink, dstarfire, astayer21 & rhynod. To the ELI5 community that has supported us so far, thanks for all your feedback and comments. Send us an e-mail: [email protected]