* Epithelial tissue: The outer layer of skin, called the epidermis, is made of epithelial tissue. It provides a protective barrier and helps regulate temperature.

* Connective tissue: The dermis, the layer beneath the epidermis, is made of connective tissue. It contains collagen and elastin fibers, blood vessels, nerves, and hair follicles.

* Muscle tissue: The arrector pili muscles attached to hair follicles are made of smooth muscle tissue. These muscles contract to make hair stand on end.

* Nervous tissue: The skin contains sensory receptors that detect touch, pressure, temperature, and pain. These receptors are made of nervous tissue.

Therefore, the skin is the organ that showcases all four fundamental tissue types in the human body.