Is light is made up of waves?
Yes. You are perfectly correct. Light is the electromagnetic radiation that has the range of frequency 4*10^12 to 750 *10^12 per second.This is a very small part of the spectrum of electromagnetic radiation whose range is extremely large .
Only the radiation of the range said above makes sensation of light in the human beings. However a diffrent upper and lower range of spectrum can make the visible sense in animals which is a nature's gift for them.
Light is obeys both particle and wave theory. The energy through the light caused by photons are absobed by objects but then the photon has no rest mass and the radiation energy recieved by anything is absorbed, reradiated , reflected or refracted in the environment.
The light, particularly the sunlight, is a mixture of electro magnetic radiations of diffrent frequencies, which travel in a straight line in a media and are subject to the laws of reflection, and refraction when it changes media of propogation.
The speed of the light is around 3*10^8 meter per second in vacuum.
In many ways light behaves like waves, and therefore it can said to be a form of wave. But not all characteristic observed in light can be explained satisfactorily considering light as a wave. For satisfactorily explaining such characteristics of light, it must me considered as particles. Accordingly the light is also considered to be consisting of particles called photons.
There is one more, unsolved problem in accepting light as well as all other forms of electromagnetic radiations as waves. This is the problem of medium in which theses waves occur. Just as waves in the see need water for its waves to exist. Similar sound waves occur in air. Thus all types of waves need some medium to exist. However light waves exist in vacuum also, where there is no medium.
Scientist have not been able to determine the nature of medium in which the light and electromagnetic waves occur. They have just assumed that this whole Universe is pervaded by a hypothetical medium called ether in which all such waves occur.