: Act as switches or amplifiers, the "brains" of many circuits. Sierra Circuits 2. Types of Circuits
by Charles Platt is a gold standard for learning what individual parts actually do. Beginner-Friendly Courses : Sites like host comprehensive syllabi and introductory notes like DC Circuits: Basics and Analysis Techniques Community Recommendations : Forums like elec circuit -simple electronics- vol.1 pdf
It is important to know that Volume 1 is strictly "Simple Electronics." It stops before microcontrollers. : Act as switches or amplifiers, the "brains"