How to Work with Expressions and the Expression Builder in Access
Every control on a form—every text box, every label, and every check box—has a set of properties that you can modify. A property is an attribute that defines an object's appearance, behavior, or characteristics. For example, the properties of a house would be its color, square footage, and shape. A property for a field on a form might be the number of decimal places displayed or the default value for the field. Because you can almost always change an object's properties, you can think of them as the object's settings.
Some property boxes will display one of the following buttons when clicked:
Click to display a list of options to change the settings for the selected property.
Click to invoke a Wizard or display a dialog box that you use to change the settings for the selected property.
Most controls have dozens and dozens of properties. You will often have to click the appropriate tab and then do some scrolling to find the property box that you're looking for.
Tabs in the Property Sheet
Format
Properties that determine the object’s appearance, such as color, text formatting, line and border color/thickness, and special effects. The purpose of many Formatting properties should be pretty obvious—for example, Font Size determines the font size of the control.
Data
Properties that determine where a control get its data, its default value (if any), and data validation rules for the control.
Event
Actions to which you can assign a macro or Visual Basic procedure. For example, clicking a button or entering information in a particular field could trigger a macro to run.
Other
Miscellaneous but important properties, such as the name of the control, if tabbing to the control is allowed, and if a message should appear in the Status bar when the control is selected.