Please provide form support to the ListBox control.
Suppose you had an application that held information about employees. There could be an employee table (Employee) with general information, a table with a list of skills (Skills) and a table that cross references the employees to their skills (EmployeesSkills). The application could have a screen where you edit the employee record. This screen could have a listbox which is filled with the data from the skills table. The user selects the skills in the listbox relevant to the employee. When the record is saved the skills selected are saved in the EmployeesSkills table (EmployeeId, SkillId).
There are other controls that can do this such as the MultiSelect control but the nice thing about the ListBox is you can see the items available and selected without having to open a dropdown.