The Epidermis is a type of epithelium tissue.
Epithelium a type of tissue (the others being Muscle, Connective and Nervous) that lines internal and external surfaces. They are typically thin sheets of cells that have a range of functions such as: separating parts of the body, lining organs (like the lungs) and generally protecting your body (e.g. The skin – including the epidermis – protects the inside of your body from external dangers).
The Epidermis is the outermost, protective layer of skin, consisting of 4 other layers in thin skin (e.g. on eyelids) and 5 on thick skin (e.g. soles of feet). It is a type of epithelial tissue and is responsible for primarily protection but also plays a part in temperature regulation through perspiration (sweating).
Hope this helps! Let me know if you need anything adding.