Thank you for the opportunity to help you with your question!
List controls in Microsoft Access, such as the combo box and list box, offer choices to the user. From their point of view, they don't have to enter anything -- they simply select an item. From the application developer's perspective, the database is protected from typos and other erroneous data.
However, on occasion, you may need a list control that's a bit more flexible, allowing users to update the control's list. Handing over a bit of control, in the right circumstances, can be helpful for everyone, including you. Users don't have to wait until you manually update the list to continue their work and you aren't interrupted to update the list.
Please let me know if you need any clarification. I'm always happy to answer your questions.