Permittivity is a measure of how easily electric fields can penetrate a material. It indicates how much electric charge a material can store when exposed to an electric field. Higher permittivity values mean that a material can store more electric energy, which is important in applications like capacitors and insulators. In physics, permittivity is often represented by the symbol ε (epsilon) and is measured in farads per meter (F/m). The permittivity of free space, known as the vacuum permittivity, is a fundamental constant in electromagnetism, influencing the behavior of electric fields in various materials, including dielectrics and conductors.