Antiprotons are subatomic particles that are the antiparticle counterparts of protons. They share the same mass as protons but have an opposite charge. While protons have a positive charge (+1 elementary charge), antiprotons have a negative charge (-1 elementary charge). This charge reversal is what distinguishes antiprotons from protons.
Like electrons and positrons, both protons and antiprotons belong to a class of particles called fermions, which have half-integer spin values. Electrons and positrons, on the other hand, are leptons and have a charge of -1 and +1 elementary charge, respectively. Leptons and quarks (such as protons and antiprotons) are two fundamental classes of particles that make up matter in the Standard Model of particle physics.
Antiprotons can annihilate with protons upon contact, resulting in the release of energy. This annihilation occurs when a proton and an antiproton collide, and their masses are converted into energy according to Einstein's famous equation E=mc². This property has applications in areas such as particle physics experiments and antimatter research.