The document summarizes the four main types of tissues in the human body - epithelial, muscular, connective, and nervous tissue. It describes the characteristics and functions of each type of tissue, as well as the subclasses within each type. For example, it notes that epithelial tissue forms protective layers and linings, muscular tissue includes skeletal, cardiac and smooth muscle, connective tissue includes bone, cartilage and blood, and nervous tissue transmits electrical signals.