The two types of dialog boxes encountered in a web app are modal and non-modal dialog boxes:

• A modal dialog box is one which disables the main content until you interact with the modal dialog.
• A non-modal dialog box, on the other hand, allows you to interact with the main content even when the non-modal dialog box is present.

We will be looking at two subcategories of modal and non-modal dialog: pop-up windows and JavaScript alerts. We will be looking at scenarios covering modal and non-modal dialog for both popups and alerts.