A Web Application Firewall (WAF) is a security system designed to protect web applications from various online threats. It acts as a filter between the web application and the internet, monitoring and controlling incoming and outgoing traffic. By analyzing HTTP requests, a WAF can identify and block malicious activities, such as SQL injection and cross-site scripting attacks, ensuring that sensitive data remains secure. WAFs can be deployed in different ways, including as hardware appliances, software solutions, or cloud-based services. They are essential for organizations that rely on web applications, as they help maintain compliance with security standards and protect against data breaches, ultimately enhancing overall cybersecurity.