AWS WAF is a web app firewall that protects your web applications and APIs from common web exploits that can affect availability, compromise security, consume excessive resources, or cause disruptions to the system. AWS WAF allows you to control how traffic is accessed your applications. You can create security rules that block common attack patterns such as SQL injection and cross-site scripting or rules that filter out specific traffic patterns. Managed Rules for AWSWAF is a pre-configured set that AWS or AWS Marketplace sellers can manage. They are easy to use and allow you to get started quickly. The Managed Rules of WAF address security issues such as the OWASP Top 10. These rules are updated regularly as new issues arise. AWS WAF comes with a fully-featured API that allows you to automate the creation, deployment and maintenance of security policies.
AWS WAF is a service that allows you to pay only for the services you use. Pricing is determined by how many rules you deploy and the number of web requests your application receives.