Let us say you want to make it larger or want to chamfer the edges. If you copy the drawing you will have to copy it again if you want to make changes to that rectangle. Some of you might think: What if I draw it once and then copy it to each drawing? So instead of drawing that rectangle twice, it would be wise to draw it once and xref it to both drawings. The two other sheets have circles, etc., but they both have one thing in common: a rectangle. I will call them sheet 1, sheet 2 and sheet 3 (see images below). Xref is used to cross reference plans and objects because you want to minimize repetitions, maximize consistency, save time and increase productivity.

If you are going to use the software for work or you are looking to advance further, you will need to know how to use the xref command. Xref is the most useful command from AutoCAD. Since external referencing is such a key feature of most AutoCAD projects, their strategic management is usually integral to the entire CAD management effort. And such strategies are tailored by you specific to your particular needs.XREF - AutoCAD tutorial step by step instructions: Frequent, regular automated back-up system of all drawings (not just the autosave feature in AutoCAD).Layer and color standards consistent between all team members.Organization of drawings into disciplines, trades, elements, floors, etc.Organization of large projects into smaller areas or divisions.A common coordinate system (such World Coordinate System or WCS) and same origin/insertion point for all drawings.Creation of drawings that are shared as xrefs by several team members (for example the structural grid of a building) rather than having multiple versions of the same thing.Maintaining Master drawing(s) while making copies for purposes of binding xrefs, sending to others, or other milestone project events.The next bullet point talks about an exception to this recommendation. It is recommended to generally use xrefs as overlay, which will not bring in any nested xrefs into a working drawing, see: Attached xrefs and overlaid xrefs in AutoCAD.

Creating an xref in autocad