There are several types of validation:

1. Format Check: Ensures data is in the correct format. For example, email addresses must include an “@” symbol and a domain suffix like “.com”.

2. Range Check: Confirms that a value falls within a specified range. For example, age fields might be restricted to values between 0 and 120.

3. Presence Check: Ensures that required fields are not left blank. For instance, a registration form may mandate entering both a username and password.

4. Length Check: Verifies that data contains the correct number of characters. For example, passwords might need to be between 8 and 16 characters long.

5. Type Check: Confirms that the data is of the expected type, such as ensuring that a field expecting an integer does not receive a string.

6. Consistency Check: Ensures related data is logically coherent. For example, a start date should not be later than an end date.

7. Uniqueness Check: Ensures data entries are unique where required. For example, user IDs or email addresses in a database must not be duplicated.

By implementing these various types of validation, systems can ensure data quality, which in turn supports reliable and efficient operation of applications and databases. Validation helps in catching errors early, reducing the cost and effort associated with fixing data-related issues later in the process.