Now, the skin is an organ. In fact, it is the largest organ of the human body by mass as well as by size. And the fact that the skin is an organ means it consists of the four different types of tissues that can necktive tissue, epithelial tissue, muscle tissue and nervous tissue. And these four different types of tissue work together to carry out a specific set of functions. Now, in the next lecture we're going to focus on the function of the skin. But in this lecture, we're going to focus on the structure of the skin.