When you go see your doctor for the first time, you probably get a clipboard with paperwork to fill out. You fill out these forms to facilitate transactions between you and your doctor. In Windows applications, a form is part of the UI in which you enter information to an application. In Microsoft Outlook, each of the windows where you enter content—for example, a new email message or a new calendar appointment—is called an Outlook form. Outlook forms include Message (for email), Contact, Meeting Request, and Appointment. Other default Outlook forms include Tasks, Journal Entries, Distribution Lists, and RSS Articles. These default forms are stored in the Standard Forms Library for Outlook. There are additional libraries as well, including Personal Forms and Organizational Forms if you have an Exchange Account.
Each folder within the Outlook hierarchy has a default Outlook form associated with it. As you would expect, a mail folder such as your Inbox has the Message form as the default, and the Contacts folder opens the Contact form as its default. To see the list of available forms in Outlook 2010, navigate to Home, New Items, More Items, Choose Form. In Outlook 2007, you would navigate to File, New, Choose Form to open the Choose Form dialog box that Figure 1 shows. The drop-down menu at the top shows the libraries where Outlook forms can be made available.
The default Outlook forms are interpersonal message (IPM) types. You might see references to forms with the prefix IPM, such as IPM.Appointment or IPM.Contact. These are the names assigned to the forms for New Appointment and New Contact respectively. You can see the IPM.Appointment reference at the bottom of Figure 1 as well. Almost all items visible in Outlook have the prefix IPM, which is especially important to developers for calling default forms or naming custom forms.
Custom Outlook forms are created to provide an interface to applications using Microsoft Outlook as the UI. One such application is Microsoft's Business Contact Manager (BCM) which uses several custom forms, including the New Business Contact Form shown in Figure 2. (I have an intro article about BCM, "What is Outlook 2007 with BCM?" and I'm planning to write more.) Outlook provides a viable option for developers of applications outside of email to incorporate the Outlook UI into their applications using forms.
Figure 2: The New Business Contact Form custom form in Outlook (click to enlarge)