What is input validation?

Updated May 6, 2026

Short answer

Input validation ensures data meets expected format and constraints.

Deep explanation

It prevents injection attacks and malformed data processing.

Real-world example

Form validation in login systems.

Common mistakes

  • Relying only on frontend validation.

Follow-up questions

  • Client vs server validation?
  • What is whitelist validation?

More Web Security interview questions

View all →