The dielectric constant, also known as relative permittivity, is a measure of a material's ability to store electrical energy in an electric field. It indicates how much electric field strength is reduced within the material compared to a vacuum. A higher dielectric constant means the material can store more energy, making it useful in applications like capacitors and insulators. Different materials have different dielectric constants. For example, water has a high dielectric constant, which is why it is effective in various electrical applications. In contrast, materials like air have a low dielectric constant. Understanding dielectric constants helps engineers select appropriate materials for electronic devices.