The charge of a proton is positive. Specifically, a proton carries a charge of +1 elementary charge, which is approximately 1.602 × 10^-19 coulombs.
Protons are one of the fundamental particles that make up the structure of atoms. They are found within the atomic nucleus, along with neutrons. Neutrons, on the other hand, have no net charge and are considered electrically neutral.
Regarding the question of why protons have a positive charge, it is a fundamental aspect of the standard model of particle physics, which is the prevailing theory that describes the fundamental particles and their interactions. According to the standard model, protons are composed of smaller particles called quarks. A proton consists of two up quarks, which have a charge of +2/3, and one down quark, which has a charge of -1/3. The net effect of these charges results in a proton having an overall positive charge.
The reason for the existence of charges in nature, both positive and negative, is still an open question in physics. It is a fundamental property of particles, and why certain particles have specific charges is not yet fully understood. However, within the framework of the standard model, charges are considered intrinsic properties of particles that cannot be further explained at the fundamental level.
It's worth noting that there is ongoing research in the field of particle physics, such as experiments conducted at particle accelerators like the Large Hadron Collider (LHC), aimed at probing the fundamental nature of particles and understanding the origins of their properties, including electric charge.