A(n) is a group of different tissues that work together to perform a certain function.

An organ is a group of different tissues that work together to perform a certain function.
Cells are the basic unit in living things. Alike cells get together and form tissues which then perform a certain function. A tissue is an intermediary form between the cells and the organs. These tissues than work together and form an organ which then carries out its specific functions. Different types of tissues can be found in all the different organs found in the body.