The Casimir effect, a manifestation of macroscopic quantum field theory, arises from zero-point fluctuations in quantum fields, leading to observable forces between material bodies known as Casimir forces. The theory of the Casimir effect is primarily formulated using Green's functions, with a close connection to van der Waals forces. The effect can be described for various materials, including conductors and dielectrics, and its dimensional dependence is discussed. The paper also explores the potential link between the Casimir effect and sonoluminescence. The introduction provides a historical context, tracing the development from van der Waals forces to the Casimir effect, and introduces the concept of zero-point energy. The Casimir force between parallel plates is derived using dimensional regularization and Green's function techniques, with detailed calculations for scalar, electromagnetic, and fermionic fields. The effects of temperature and the presence of matter are also considered, including the high-temperature limit and the impact of finite electron density in conductors. The paper concludes with a discussion of the Casimir effect in dielectrics, extending the formalism to include external polarization sources.The Casimir effect, a manifestation of macroscopic quantum field theory, arises from zero-point fluctuations in quantum fields, leading to observable forces between material bodies known as Casimir forces. The theory of the Casimir effect is primarily formulated using Green's functions, with a close connection to van der Waals forces. The effect can be described for various materials, including conductors and dielectrics, and its dimensional dependence is discussed. The paper also explores the potential link between the Casimir effect and sonoluminescence. The introduction provides a historical context, tracing the development from van der Waals forces to the Casimir effect, and introduces the concept of zero-point energy. The Casimir force between parallel plates is derived using dimensional regularization and Green's function techniques, with detailed calculations for scalar, electromagnetic, and fermionic fields. The effects of temperature and the presence of matter are also considered, including the high-temperature limit and the impact of finite electron density in conductors. The paper concludes with a discussion of the Casimir effect in dielectrics, extending the formalism to include external polarization sources.