Light is made by an electron dropping to its natural orbit from an orbit that has higher energy, emitting energy in the process. This energy is released in the form of a photon, or particle of light, whose frequency corresponds to the distance between the two orbits.
The most common way of creating light is by applying heat. When an object is heated, the atoms in that object get energized. If enough heat is applied, their electrons release enough energy for that energy to be visible as light. The light with the lowest energy in the visible part of the electromagnetic spectrum is red light. Eventually, as different types of electrons release different levels of energy, all the colors of the spectrum are generated. These colors meld into white and the object becomes white-hot.
Heating a thin filament with electricity is how incandescent lightbulbs work. The filament offers significant resistance to the electricity thanks to its extreme thinness, and the resistance generates heat and makes the filament glow white-hot. Lightbulbs are generally highly inefficient sources of lighting; most of the applied energy is turned into heat, not light. A standard lightbulb typically produces 15 lumens of light per watt, while a fluorescent bulb emits 50 to 100 lumens per watt.