The most basic use of a textbox is for a user to enter somewhat free-form text information. This is suitable for data items like street address, or names like first name or last name.
However, a textbox is not suitable for data fields that can be pre-selected. For example, a state in the US should not be entered using a textbox due to the potential of user errors. Instead, a listbox or a dropdown box is much more suitable. Either option only permit a user choose from a list of choices.