How can I copy blocks and layers from one drawing to another drawing?

The Drawing Explorer allows you to copy definitions between open drawings:

1. Open both the source and the target drawing.
2. Launch the Drawing Explorer.
3. In the source drawing select the category you want to copy items from, e.g., Blocks.
4. (option) In the Details toolbar, click the Icon View button ()
5. Select the item(s) you want to copy, e.g., a series of blocks.
   Press and hold the Ctrl key to select multiple items.
6. Press and hold the left mouse button to drag the selection set to the Open Drawings section of the Drawing Explorer.
7. Release the left mouse button when on the target drawing name.
   The selected items are copied to the target drawing.
   You will be prompted to overwrite items of the same name.