Particles and antiparticles are fundamental entities in particle physics. Particles are the building blocks of matter and include particles like electrons, quarks, and neutrinos, among others. Antiparticles are the counterparts of particles, having the same mass but opposite charge.
According to the theory of quantum field theory, for every particle, there exists a corresponding antiparticle with the opposite charge. For example, the antiparticle of an electron is called a positron, which has the same mass as an electron but a positive charge.
When a particle and its corresponding antiparticle come into contact, they can annihilate each other, releasing energy in the process. This annihilation process is a key concept in high-energy physics.
As for the question of where the antiparticles are hiding from us, it is important to note that particles and antiparticles are both observed and created in various experiments. Particle accelerators, such as the Large Hadron Collider (LHC), have been instrumental in producing and studying both particles and antiparticles. The reason why we see more matter than antimatter in the universe is still an open question in physics, and it is an active area of research. This phenomenon is known as the "matter-antimatter asymmetry problem." Various theories and experiments are being pursued to understand why there is an imbalance between matter and antimatter in the observable universe.