Null values represent the absence of data in a database or dataset. They indicate that a particular piece of information is unknown, missing, or not applicable. For example, if a customer does not provide their phone number, that field may be recorded as null. In programming and data analysis, handling null values is crucial to avoid errors and ensure accurate results. Many programming languages and database systems have specific functions or methods to check for and manage null values, allowing developers to maintain data integrity and perform calculations without unexpected outcomes.