In AutoCAD, a block is a collection of objects that are combined into a single named object. The following are some examples of blocks at different scales. In the context of AutoCAD, blocks are the set of geometries that act as a single object and can be used in a drawing on a repetitive basis. The blocks used in the drawing are called block references, and if the block is modified, all of its references change automatically.
BricsCAD also offers a powerful Blockify tool to automatically detect duplicate collections of entities in a drawing and convert them into blocks. In this case, simply modify the window block and all references used in the drawing will change automatically. This is why many organizations prefer their own set of standard blocks that can be used and reused according to their own requirements. Some of these blocks are realistic representations of objects, others are symbols, and one of them is an architectural title block for a D-size drawing.
Yes, you can edit blocks in BrisCAD, use the bEdit command to edit blocks in a temporary drawing session called Block Editor. Instead of creating a drawing file to insert as a block, you may want to create a block definition directly in the current drawing. The lines and text that make up a block are grouped in such a way that you can select the entire object (block) at once to perform actions such as placing, copying and moving the block. But even if you've been using blocks for years, I think you'll find the links at the end with more advanced tips useful.
For example, you can create a dynamic block of a door of different sizes and, when used in the drawing, you can use the same dynamic block for all door sizes. The block definition is stored once and each insertion of that block reuses that definition with minor modifications: different points of insertion, rotation or scale. This principle is called nesting, and that's why the block definitions in the drawing are sometimes shown in the form of a tree. Now navigate to the drawing and select blocks and you'll have your full list of drawing blocks in the palette.
Blocks are one of the most important types of objects in AutoCAD and are also used very frequently in almost all types of drawings. For example, a dynamic block dining corner can be configured to be shown as a square table with 2 or 4 chairs, or a round table with 4 or 6 chairs, or a long table with 10 chairs, etc. A drawing made with blocks for repetitive objects will be much smaller than the drawing that uses copied instances of repetitive elements objects.