We all know that the Holy Roman Empire was a collection of minor Germanic states in the Medieval and Renaissance Europe. Wikipedia stated that:
The Holy Roman Empire was a multi-ethnic complex of territories in central Europe during the medieval and early modern periods until its dissolution in 1806.
A question which I have been bothered, and I am sure most of you do, is how exactly were their borders defined? In two maps below the borders seems to sometimes cross another border. Furthermore, the borders seem to be changing with time.
This first map is one of Europe in the 16th century. The Holy Roman Empire is outlined in purple.

This second map is one of Europe in 1700:

References: