Specialized groups of cells that are organized to perform specific functions are called tissues.

Here's a breakdown:

* Cells: The basic unit of life, responsible for carrying out specific functions.

* Tissues: Groups of similar cells that work together to perform a particular function.

* Organs: Structures made up of different tissues that work together to perform a complex function.

* Organ Systems: Groups of organs that work together to carry out major bodily functions.

Here are some examples of tissues:

* Epithelial tissue: Covers surfaces of the body and lines organs.

* Connective tissue: Provides support, protection, and insulation.

* Muscle tissue: Responsible for movement.

* Nervous tissue: Carries electrical impulses throughout the body.

Let me know if you'd like to learn more about specific tissues or their functions!