What does data validation do in Excel?

Data validation in Excel serves the primary purpose of restricting the type of data that can be entered into a cell. This feature is incredibly useful for maintaining data integrity, as it allows you to set specific rules about what users can input. For example, you can limit entries to whole numbers, dates, or specific lists of values. This ensures that the data collected adheres to defined criteria, reducing the likelihood of errors and inconsistencies.

The other options, while relevant to various functionalities in Excel, do not describe the role of data validation. Conditional formatting focuses on changing the appearance of cells based on their values rather than restricting input. Generating a random value pertains to functions like RAND or RANDBETWEEN, which create random numbers rather than validating existing data. Automatically summing up values falls under the domain of functions like SUM, which aggregates data rather than imposing restrictions on input. Thus, the core function of data validation is best captured by its ability to limit and control the type of data entered into a cell.