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The electron is an electrically charged elementary particle in the lepton family. It has electric charge $-e$, spin $1/2$ and rest mass $m_e$. The Positron is its antiparticle, with the same mass and opposite charge.

In an atom, atomic orbitals describe electron quantum states rather than tiny classical planetary trajectories. In a material, mobile electrons carry current and can respond to applied electric fields and magnetic fields. An electron gun produces a directed beam whose deflection and interactions make electron imaging and scattering experiments possible. A recorded spot is a detection event; the propagation amplitudes that predict its probability can still interfere.

An elementary particle has no resolved constituent substructure within the physical theory and experiments under discussion. In the Standard Model, examples include electrons, quarks and photons. A proton is instead a composite hadron, even though it often acts as one particle in a detector or an atomic model.

The distinction is tested through interactions rather than by picturing a smaller material ball inside a larger one. Scattering at increasing momentum transfer probes shorter spatial scales and can reveal internal response. A fundamental quantum field describes the particle's excitations; being elementary does not mean that all measured electromagnetic properties reduce to those of a classical point charge.

A hadron is a strongly interacting composite particle described by quantum chromodynamics. Familiar hadrons contain quarks and gluons in an overall color-neutral state. The proton and neutron are baryons; the pion is a meson.

The quark model labels ordinary hadrons by their valence content, but this does not list every dynamical constituent. Gluons and additional quark–antiquark contributions affect masses and interactions. Distinguishing a composite hadron from an elementary particle is useful when comparing low-energy models with scattering experiments that resolve internal structure.

Awarded jointly to Chen Ning Yang and Tsung-Dao Lee for investigating parity conservation laws, leading to discoveries about elementary particles.^[ref]

One half went to Eugene Paul Wigner for theories of atomic nuclei and elementary particles, particularly symmetry principles; the other half jointly to Maria Goeppert Mayer and Johannes Hans Daniel Jensen for discoveries about the nuclear shell model.^[ref]

Awarded in equal shares to Sin-Itiro Tomonaga, Julian Seymour Schwinger and Richard Feynman for fundamental work in quantum electrodynamics, with consequences for elementary particles.^[ref]

Awarded to Luis Walter Alvarez for discoveries in elementary particle physics, especially particle resonances identified using hydrogen bubble chambers and analysis of their records.^[ref]

Awarded to Murray Gell-Mann for discoveries concerning the classification of elementary particles and their interactions.^[ref]

Awarded in equal shares to Burton Richter and Samuel Chao Chung Ting for pioneering work discovering a new kind of heavy elementary particle.^[ref]

Particle physics studies the elementary constituents of matter and their interactions. It connects quantum fields and symmetry principles with measurements of scattering, decays and particle production.

An accelerator experiment does not photograph an elementary particle's internal form directly. Detectors record tracks, energy deposits and timing signals; a model reconstructs the event and compares distributions with predicted processes. Collider studies, neutrino measurements and nonaccelerator experiments provide complementary tests of the Standard Model and searches for additional phenomena.

A subatomic particle is a constituent or excitation studied at the level below ordinary atomic structure. The category includes elementary particles, such as the electron, and composite hadrons, such as the proton and neutron.

Calling something a particle does not require a tiny classical solid sphere. Quantum mechanics describes localized detections and wave-like propagation, while high-energy scattering probes whether internal structure is resolved. A particle detector usually infers a particle from transferred energy, emitted light or a trajectory reconstructed from many interactions. The measured track width and the particle's intrinsic spatial structure are therefore different quantities.