1. What is a field? This field is actually a broad category. As a mathematical concept, field is a space with certain properties, such as no rotating field, no scattering field, and it has no actual existence form. As a physical concept, field is an existing form of matter, which is the definition of field. In physics, the field is endowed with the meaning of matter and has the basic properties of matter.

It can't be said that only electric field and magnetic field are fields, but in physics, field mainly refers to electromagnetic field, which is a substance.

2. Wave (mainly electromagnetic wave here) is a spatially distributed field whose amplitude and direction change with time. In essence, wave is a special form of field. So if there is a wave, there must be a field, but not all fields can form waves. For example, an electrostatic field generated around an electrostatic charge cannot be considered as a wave.

I remember that the theory of relativity said that an object with mass and energy cannot exceed the speed of light, but this does not mean that light is not matter. First of all, the existing theory does not completely rule out the possibility of superluminal in the true sense; Secondly, the speed of light itself does not exceed the speed of light, but the maximum is equal to the speed of light.

Light is essentially an electromagnetic wave, just an electromagnetic wave with a certain frequency range. In this frequency range, electromagnetic waves are visible, that is, light. So, light is a substance.

In addition, I think it is necessary to explain that the speed of light is just a speed constant, which is not directly related to the matter itself, just because the speed of light (electromagnetic wave) in vacuum is equal to the speed of light, which is customarily called the speed of light.