One or more objects can be combined and stored as a block. A block is treated as a single object for purposes of selecting and editing.
Each block is stored in the drawing's internal library, and each instance of the block is a reference to this source. This means that numerous instances of a block can be added to the model without significantly increasing the file size. Groups are similar, but they are not linked to sources; each group contains its own drawing data. See Groups.

Note: A drawing's block library is internal to the drawing, and is stored with the file. Symbol libraries are similar but are stored separately, and can be accessed while in any drawing. If you need to create a group of objects that will be used in multiple drawings, create a symbol. See Loading Symbol Folders into the Library.If you want to import the entire contents of another file (DoubleCAD or other format) as a block, see External References.

Because blocks can contain individual objects, groups, and other blocks, they can be complex hierarchical structures. For block manipulation, use the Blocks Palette (View / Blocks).

Tip: You can use the TC Explorer Palette to view blocks of any open drawing, and to drag blocks to and from drawings. See Drawing Settings.