Neurotrophic factors are proteins that support the growth, survival, and differentiation of neurons in the nervous system. They play a crucial role in the development and maintenance of the nervous system by promoting the health of nerve cells and facilitating communication between them. One well-known example of a neurotrophic factor is Brain-Derived Neurotrophic Factor (BDNF), which is essential for learning, memory, and overall brain function. These factors are also being studied for their potential therapeutic applications in conditions like Alzheimer's disease and Parkinson's disease, where neuronal health is compromised.