Explain the role of input validation in web application security and provide examples of common vulnerabilities it helps mitigate.

Input validation plays a critical role in web app security by ensuring that user inputs are safe and meet expected criteria. XSS attacks can be mitigated by validating and sanitizing input to prevent malicious scripts from executing. SQL injection vulnerabilities are averted by validating and escaping input to prevent unauthorized database queries. Buffer overflow risks are minimized by checking input length and limiting data size. Proper email format validation reduces the chance of email-based attacks.