The Backpack is a copy/paste feature. It allows you to copy blocks from one project or screenand paste them into another project or screen.To copy, you can drag-and-drop blocks into the Backpack. To paste, click on the Backpack icon anddrag-and-drop blocks into the workspace.</p><p>If you leave MIT App Inventor with blocks left in your backpack,they will be there the next time you login.</p><p><a href='/reference/other/backpack.html' target='_blank'>Click Here</a> for further documentation and a 'how to' video.