The basic unit of all living things is the cell. Cells are the structural and functional units that constitute all organisms, ranging from unicellular bacteria to complex multicellular organisms, such as humans. Each cell contains essential components, including DNA, organelles, and cytoplasm, which work together to execute various biological processes. The study of cells, known as cell biology, provides insights into life functions and disease mechanisms, laying the groundwork for advancements in medicine, biotechnology, and genetics.