Sometimes you may need a way for flexible linking of multiple AutoCAD drawing objects to a single chunk, which can be manipulated - e.g. moved - as a single object.

Such grouping together can be achieved through various methods - e.g.:

Creating a block - combine the individual entities or blocks to a single common block (the BLOCK command) and then manipulate them as a single entity. If you need to temporarily disable this grouping, or edit the individual objects, you've got a problem (you will need to explode or edit the block). This method is not very flexible.
Creating a group - this is the most common method - use the GROUP command to create a temporary group, usually an unnamed group, from the selected objects and as long the "Group" mode is active (Ctrl+Shift+A, resp. the PICKSTYLE variable), any usual editing operations are performed on all objects of the group. By disabling this mode you can work with the individual objects again. This is a flexible grouping method, but the objects need to be grouped manually.
Inferring constraints - a dynamic method of automatic inferring of constraints (links) between geometrically related objects - a part of AutoCAD parametric functionality. You can apply it directly during drawing (creation) of geometrically close objects - by enabling the "Infer geometric constraints" mode (in the ribbon Parametric > Geometric > Geometric > Infer geometric constraints, by an icon in the statusbar - see video, or by the variable CONSTRAINTINFER). Existing constraints can be removed by the DELCONSTRAINT command. See insertion of the two blocks (A and with a common insertion points - without constraints and with inferred constraints: