Lenticular galaxies are a type of galaxy that have characteristics of both spiral galaxies and elliptical galaxies. They typically feature a central bulge and a disk but lack the prominent spiral arms found in spiral galaxies. This gives them a smooth, lens-like appearance, which is how they got their name. These galaxies are often classified as S0 in the Hubble sequence. Lenticular galaxies contain older stars and less interstellar gas and dust compared to spiral galaxies, making them less active in forming new stars. They are commonly found in galaxy clusters and can serve as a bridge between different galaxy types.