Meaning
A white medium square with an outline, the light twin of ◼️. It means white or empty and often looks like an unticked checkbox.
People use it as a blank checkbox in to-do lists, a quiet bullet in neat posts or a frame in simple diagrams: “◻️ Buy gift ◻️ Wrap gift ☑️ Book table” On white backgrounds it can almost vanish, so it works best in lists with other symbols. Compare ⬜ and ◽ for other sizes.