What do cells join together to form in multicellular organisms?

In multicellular organisms, cells join together to form tissues, which are groups of similar cells that work together to perform specific functions. This organization allows for more complex structures and functions than single-cell organisms can achieve.

For example, muscle tissue is made up of muscle cells that contract together to enable movement, while connective tissue supports and connects different parts of the body. Understanding that tissues are the fundamental building blocks of organs, which are then organized into systems, emphasizes the hierarchical nature of biological organization in multicellular life.