A fetus is a developing human from about eight weeks after conception until birth. During this stage, the fetus undergoes significant growth and development, forming essential organs and systems. It is nourished through the placenta, which connects it to the mother and provides oxygen and nutrients. Fetuses can be observed through various medical imaging techniques, such as ultrasound. This allows healthcare providers to monitor their development and detect any potential issues. By the end of the pregnancy, a fully developed fetus is ready for birth, transitioning into a newborn.