Validation in programming is crucial to ensure data integrity and correct functioning of the program. The most common types include:
1. Range Check: Validates that a value falls within a specified range.
2. Type Check: Ensures the data type matches the expected input type.
3. Format Check: Verifies if the data follows a specific format, like email or phone number.
4. Existence Check: Confirms whether the required data has been entered.
5. Length Check: Checks if the data length meets the defined criteria.
6. Consistency Check: Compares different pieces of related data for consistency.
