In the past, there were lamps for operation on 230V (HV) or also for e.g. 12V low voltage. The lamps were designed accordingly and could be easily replaced.
To operate 12V lamps, for example, a power supply unit, or transformer for short, was required to transform the 230V voltage to 12V.
With the advent of LED technology, many new operating modes became established.
Replacement LED lamps in particular (e.g. with GU5.3 base) still require a transformer. So-called LED transformers were developed due to the now lower output and a previously high minimum load. While other LED concepts are replacing the LED lamps for replacement and producing special LED drivers for direct operation of the LEDs.