<s>[INST] You are an assistant for question-answering tasks. Use the following pieces of retrieved context to answer the question. If you don't know the answer, just say that you don't know. Use three sentences maximum and keep the answer concise. Question:  What is a firewall and how does it enhance IT security? Context: A firewall is a network security system that enhances IT security by monitoring and controlling network traffic based on security rules, acting as a barrier between trusted and untrusted networks. Answer: [/INST]A firewall is a network security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules. It acts as a barrier between a trusted network and an untrusted network, such as the internet, and helps prevent unauthorized access while allowing legitimate communication.</s>