Half OT: Basic principle of transistor reinforcement

Since hamma the salad, the merendo absolutely wants to know how such a transistor amplifier circuit works in principle. To this end, the merendo has already rummaged quite diligently on the Internet, but only found very complicated and complex schematics without understandable explanations. Therefore, the merendo turns to you full of hope and despair. The merendo thinks, who knows with HiFi, could also know something. The merendo asks for a schematic of a transistor amplifier ers, and that is “as basic as possible”. No complex confusions that are not necessarily necessary, the merendo is only about understanding the basic principle. If possible, please with explanations. And don’t worry, the merendo is not schizophrenic (I do it all the more) The merendo says thanks for all the help!!