No, a photon is not considered matter. A photon is a fundamental particle of light and is classified as a boson. Unlike matter, which is composed of particles that have mass, photons are massless particles that travel at the speed of light.
To understand this better, we can look at the distinction between matter and energy. Matter is made up of atoms, which consist of protons, neutrons, and electrons. These particles have mass and occupy space. In contrast, photons are carriers of electromagnetic radiation, such as light, and do not occupy space in the same way that matter does.
Furthermore, photons exhibit both particle-like and wave-like properties, a phenomenon described by quantum mechanics known as wave-particle duality. This means that while they can behave like particles when interacting with other matter, they fundamentally lack the characteristics of matter.
In summary, while photons are essential to many processes in the universe and even have momentum, they do not meet the criteria to be classified as matter due to their massless nature.