Lighting transformers are, just as the name implies, transformers that are specifically utilised to work with lighting. They are typically referred to as dimmer switches. By using the ability of a transformer to alter the voltage passing through a circuit, a light can be made brighter or dimmer.
According to Networks of Power: Electrification in Western Society, 1880-1930, by Thomas Park Hughes, the Ganz factory, located in Budapest, Hungary, started manufacturing equipment for electric lighting in homes around the year 1878. In the following years many different designs of dimmer switches were introduced, but most of them had flaws because they were still very primitive.