What is AWS WAF? What are the potential benefits of using WAF?

AWS WAF is a web application firewall that lets you monitor the HTTP and HTTPS requests that are forwarded to Amazon CloudFront and lets you control access to your content. Based on conditions that you specify, such as the IP addresses that requests originate from or the values of query strings, CloudFront responds to requests either with the requested content or with an HTTP 403 status code (Forbidden). You can also configure CloudFront to return a custom error page when a request is blocked.
Benefits of using WAF:

• Additional protection against web attacks using conditions that you specify. You can define conditions by using characteristics of web requests such as the IP address that the requests originate from, the values in headers, strings that appear in the requests, and the presence of malicious SQL code in the request, which is known as SQL injection.
• Rules that you can reuse for multiple web applications
• Real-time metrics and sampled web requests
• Automated administration using the AWS WAF API