Input validation is the process of checking incoming data to ensure it is safe, correct, and expected before it is processed. Applications validate input to prevent malformed or malicious data from causing errors or security vulnerabilities. Proper input validation includes verifying types, lengths, formats, and allowed values. It is a key defense against attacks like SQL injection or cross-site scripting.
Why it matters
Validating user input protects systems from corruption, improves reliability, and prevents exploitation. It also enforces business rules, ensuring that entered data meets the requirements of the system.
Examples
Checking that an email is properly formatted or ensuring a number is within a valid range. Lessons like Input Validation and Sanitization demonstrate best practices.