All electromagnetic waves move at the speed of light; subsequently, the wavelength and frequency of waves must be proportional, as the wavelength multiplied by the frequency equals the speed of light. As wavelength increases, frequency decreases, and as wavelength decreases, frequency increases proportionally.
Different types of electromagnetic radiation have different wavelengths and frequencies. For example, gamma waves have a high frequency and a low wavelength, whereas radio waves have a low frequency and a high wavelength. Visible light falls near the middle of the electromagnetic spectrum, meaning most types of electromagnetic radiation have either a shorter or longer wavelength, as well as a lower or higher frequency.
Together, the frequency and wavelength of electromagnetic waves form oscillations as they travel. The shape of the oscillations is dependent on the type of electromagnetic radiation, and thus the frequency and wavelength of the waves. While the shape of the oscillations varies depending on the type of electromagnetic radiation, due to the proportional nature of electromagnetic waves, the size of the waves doesn't vary.
The quantum theory of electromagnetism posits that electromagnetic radiation is composed of photons: particles that also show characteristics of waves. According to the quantum theory of electromagnetism, photons, in a similar manner to other elementary particles, show wave-particle duality and are a fundamental part of understanding electromagnetic processes.