How is a cell defined?

A cell is defined as a unit of protoplasmic material with distinct features, emphasizing its role as the basic structural and functional unit of all living organisms. Cells are the smallest units that can carry out all the processes necessary for life, including metabolism, growth, and reproduction. Each cell possesses unique characteristics based on its type, such as muscle cells, nerve cells, or skin cells, contributing to its specific function within an organism. This definition encompasses both single-celled organisms, like bacteria, and the multitude of specialized cells found in multicellular organisms. The concept highlights the importance of cells as the foundational building blocks of life, separating them from larger structures such as organs and tissues.