Request inspection is the process of examining incoming network or HTTP traffic before it reaches an application. A web application firewall or proxy may parse headers, URL paths, cookies, and body content, then compare the request against security rules, threat signatures, and policy limits. It often includes normalization so that encoded or obfuscated input is evaluated in a consistent way.
This matters because many attacks hide in request details. SQL injection, cross-site scripting, command injection, and protocol abuse often rely on malformed syntax, unusual encodings, or tricky multipart data. If the inspection engine misreads the request differently from the backend application, malicious traffic can slip through as a false negative. Defenders also use request inspection to block policy violations, rate-limit abusive clients, and detect denial-of-service patterns. In practice, its reliability depends on correct parsing, transformation, and rule coverage.