Here's a breakdown:

* Cells: The basic building blocks of life.

* Tissues: Collections of similar cells that work together to perform a specific function.

* Organs: Structures made up of different tissues working together for a common purpose.

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

Examples of tissues:

* Epithelial tissue: Covers surfaces like skin, lining of organs, and blood vessels.

* Connective tissue: Supports and connects other tissues, including bone, cartilage, blood, and fat.

* Muscle tissue: Responsible for movement, including skeletal, smooth, and cardiac muscle.

* Nervous tissue: Transmits electrical signals throughout the body, including the brain, spinal cord, and nerves.