help reading chess books with only few positions diagrammed

I'm not sure where to best ask this question.  I hope it's OK to do so here!

I am returning to chess after a long hiatus, and am reading a chess book which inevitably says stuff like "if instead he played THIS, then it would have gone like THIS" and gives a continuation along that different line of play.  If I follow that side-line to understand it, and afterwards I want to go back to the branching point, it's a pain to put a physical board back to where it was before on the main line of play.  I assume there must be some software tool that can be used to set breakpoints which you can use to move forward and back like this easily with a virtual chessboard.  Would  someone please point me in that direction?  Thanks!

When the alternative line of play is several moves ahead by each side? No.

Use two boards; you will learn more than using a computer.

Any chess program easily allows this. At chess.com, for example, click Learn->Analysis and then start making moves. These will be recorded and visible on the screen. When you want to explore a branch, go back to the move before the branch and then make the alternative move. This will create a new branch. This will create a new line, but at any time you can click back to the main line.

Thank you, landloch, for being RELEVANT and kind, and answering my question with an actual answer, rather than a lecture! I appreciate your help!