Why diode rectifiers are called as uncontrolled rectifiers?

Diode rectifiers are called uncontrolled rectifiers because they rely on the natural conduction properties of diodes, which allow current to flow only in one direction without any external control mechanism. Once the input voltage exceeds the diode's forward voltage threshold, the diode conducts and rectifies the AC signal into DC. This behavior is inherently passive, as the diode does not require any active components or control signals to operate, making it "uncontrolled" compared to other rectification methods, such as those using thyristors or transistors.