There are four main types of tissues in the body: epithelial, connective, muscle, and nerve. Epithelial tissue forms boundaries and consists of sheets of cells. There are two main types of epithelial tissue: simple and stratified. Simple epithelial tissue is only one cell thick and includes simple squamous, simple cuboidal, and simple columnar tissues. Stratified epithelial tissue has two or more layers and provides protection, with four subtypes. Connective tissue is found throughout the body and has four main types - proper, cartilage, bone, and blood tissues. Connective tissue proper includes loose tissues like areolar and adipose tissues, and dense tissues.