Explain what is meant by the process of verifying the correctness of data or input parameters.

The process of verifying the correctness of data or input parameters is a set of actions aimed at confirming that the data meets expected requirements and contains no errors.

Key aspects of validation:

• Data type: checking that the value matches the expected type (number, string, date, etc.).
• Value range: for example, age should be between 0 and 120.
• Format: checking the string format, such as email or phone number.
• Mandatory fields: ensuring that required fields are not empty.
• Logical consistency: for example, the end date cannot be earlier than the start date.

Example: when entering the "age" parameter, check that it is an integer within the range of 0 to 120. If the check fails, the system should notify the user or reject the data.

Such validation helps prevent errors in the application and ensures data quality.