Microfilaments are thin, thread-like structures found in the cytoskeleton of eukaryotic cells. They are primarily composed of a protein called actin, which plays a crucial role in maintaining cell shape, enabling movement, and facilitating cell division. Microfilaments are involved in various cellular processes, including muscle contraction and the formation of cellular extensions like microvilli. These structures are about 7 nanometers in diameter, making them the smallest components of the cytoskeleton, which also includes intermediate filaments and microtubules. Microfilaments can rapidly assemble and disassemble, allowing cells to adapt to their environment and respond to external signals effectively.