Why -3dB? (An alternate approach to explaining dBs)

Why is there specifically a -3db point chosen for frequency response? Support Roger on Patreon: https://www.patreon.com/kainkalabs Why is the dB-definition sometimes 10*log(x) and sometimes 20*log(x)? If you ever wondered about some of the mysteries about the decibel, this tutorial is for You Support Roger on Patreon: https://www.patreon.com/kainkalabs