A quasiparticle is a collective excitation that can be described approximately by particle-like quantum numbers and dynamics, even though it is not an isolated elementary particle. Excitons and polaritons are examples.
A polariton is a hybrid light–matter excitation formed by strong coupling between a photon and a material excitation. For an exciton-polariton, the material component is an exciton.
An exciton is a bound state of an electron and an electron hole. Coupling this material excitation strongly to a photon can form a polariton.
An electron hole is the absence of an electron in an otherwise filled band, described as a mobile positive-charge excitation. It can form a bound state with an electron, giving an exciton.
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The opposite of elementary particle.