Explain the purpose of Thevenin's theorem in circuit analysis.

Thevenin's theorem is a powerful tool in circuit analysis that simplifies complex linear circuits into a simpler equivalent circuit consisting of a single voltage source and a single series resistance. Its primary purpose is to make it easier to analyze the behavior of a circuit when changes are made to a specific part of the circuit, particularly the load connected to it. A linear circuit is one in which the components' electrical characteristics, such as resistance, capacitance, and inductance, remain constant regardless of ....