Quote Originally Posted by Hopeless
I am new to Access and I need help in understanding the difference between a BOUND and UNBOUND control on a form.
From the help file
Controls: What they are and how they work

Controls can be bound, unbound, or calculated.

A bound control is tied to a field in an underlying table or query. You use bound controls to display, enter, and update values from fields in your database.

An unbound control doesn't have a data source. You can use unbound controls to display information, lines, rectangles, and pictures.
Quote Originally Posted by Hopeless
I am specifically confused about which column is the Bound column and what the combobox's Control Source should be.
A combobox's control source is usually bound to a foreign key or a lookup table.

The bound column for a combobox is the value that is tied to that combobox, applicable to comboboxes with multiple columns. You can set which column is the bound column under properties. It is usually a primary key that is bound since a multiple column combobox typically displays several fields from one table.

You can still refer to the other columns in VBA;
[vba]me.cboValue 'Refers to the Bound Column

me.cboValue.Column(2) 'Refers to the third column. Not the Second Column.
me.cboValue.Column(0) 'Refers to the first column.[/vba]