What should you use to ensure columns do not appear on the page while still being included in exports?

Using CSS is the appropriate choice for ensuring that columns do not appear on the page while still being included in exports. CSS can be effectively utilized to control the visibility of specific elements on a webpage. By applying CSS styles, you can set an element's display property to 'none', thus ensuring that while the data remains present in the underlying structure of the webpage — potentially for exporting or processing purposes — it does not visually render in the user interface.

This approach is advantageous because it allows you to maintain the data integrity and structure without showing all content to the end-users, thus enabling a cleaner and more focused user experience. Additionally, it allows for quick updates and changes to visibility without altering the actual data processing or export logic.

Other methods like using data annotations, JavaScript, or HTML attributes do not offer the same level of simplicity and effectiveness for this particular use case. Data annotations are primarily used for validation and metadata, JavaScript would require more complex interactions to manage visibility dynamically, and HTML attributes alone do not provide styling capabilities.