Modal UI design is crucial in capturing user attention and engagement. A modal is a website element that pops up on top of on-screen content, often disabling the content beneath it. They are valuable tools for presenting important information or guiding users through onboarding flows. However, they can also be intrusive if not designed properly. To create effective modals, consider using clear titles, explanatory graphics, sharp body copy, explicit calls to action, and an escape hatch. Pay attention to sizing and location, implement action-triggered modal windows, trap keyboard navigation within the modal window, use progress bars for modal tours, maintain consistency with user expectations, design for different devices, and focus on drawing immediate attention to the modal. Some examples of successful modal designs include Google, Linktree, LANDR, and Airtable.