What is a subform?
A subform is a lot like it sounds, a form inside another form. Other names can be parent/child form or master/detail form. Subforms are best used to show data from tables or queries that are considered to have one-to-many relationship.
Make a Subform
First open a database window.
Click on Forms in the Objects task pane, click the New button located on the toolbar and a New Form dialog box will open.
Double click the Form Wizard.
From the list, select Tables/Queries. Select the fields that you want to add to the form by double clicking them from the Available fields list.
Do not click Next just yet.
First you will need to select a second option from the Tables/Queries lists, double click the fields and add accordingly to that selection.
Make sure to set up the relationships between the two tables or queries, now click Next.