Snap Assist is a feature in Windows 10 and later versions that helps users manage multiple open windows on their desktop. When you drag a window to the edge of the screen, it automatically resizes to fill half of the display. This makes it easier to view and work with two applications side by side. Additionally, Snap Assist shows thumbnails of other open windows, allowing users to quickly select one to fill the remaining space. This feature enhances productivity by simplifying multitasking and organizing the workspace efficiently.