When cells of the same type join to perform a common task, they form a tissue.

Here's a breakdown:

* Cells: The basic building blocks of all living organisms.

* Tissue: A group of similar cells that work together to perform a specific function.

* Organ: A structure made up of different tissues that work together to perform a complex function.

* Organ System: A group of organs that work together to carry out major bodily functions.

* Organism: A complete living being made up of multiple organ systems.

For example, muscle tissue is made up of muscle cells that contract and relax to allow movement. Nervous tissue is made up of nerve cells that transmit electrical signals to communicate throughout the body.