Modals are overlay windows that appear on top of the main content, requiring user interaction before continuing. Used for critical decisions, forms, alerts, or focused tasks. Block interaction with underlying page until dismissed. Powerful but easily overused.
Use modals for critical confirmations (delete account, unsaved changes), focused tasks (quick add, simple forms), alerts/errors that require acknowledgment, or content that shouldn't interrupt main flow (image lightbox, video player). Keep them small, focused, and dismissible. Don't use for lengthy forms, content users need to reference, or frequent actions.
Information Architecture
Temporary overlays—dialogs, drawers, popups, focused tasks without leaving context