In biology, a tissue is a group of similar cells that work together to perform a specific function. We can find tissues in animals, plants, and fungi. In animals, the four primary types of tissues are epithelial, connective, muscle, and nervous tissue.

Epithelial tissue covers the surface of the body, lines organs, and forms glands. Connective tissue supports and connects organs and tissues, and includes bone, cartilage, and blood. Muscle tissue handles movement, including both voluntary and involuntary movement, and includes skeletal, smooth, and cardiac muscle. Nervous tissue transmits and processing information throughout the body, and includes the brain, spinal cord, and nerves.