Validation and Authentication

Validation and authentication are essential concepts for producing robust, secure programs. Validation ensures that data is reasonable and sensible before it is processed, while authentication verifies the identity of a user. Both are required for GCSE Computer Science (AQA 3.2 / OCR J277 2.2).

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What Is Validation?

Validation is a check performed by a program to ensure that data entered by a user is reasonable, sensible, and within expected bounds. Validation does NOT check whether data is correct — it checks whether it is plausible.

Key Distinction: Validation checks if data is reasonable; verification checks if data is accurate (e.g. asking the user to type their email twice). Know the difference for the exam.

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Types of Validation