I have used large Excel workbooks with lots of internal links between cells.
I have had to Paste Special into a new workbook when copying a sheet to avoid
creating a link between workbooks. I have not understood what caused this;
only how to avoid.

What characteristics of a workbook causes the link to be established between
2 workbooks? As I train staff in our office who are getting caught with
linked workbooks, I need to understand the cause.

Thanks.