Definition: Backtracking means you say back what someone says to you. So if you did that with this web page you would say, "Excuse me Web page, let me make sure I understand, backtracking means you say back what someone says to you?"
And then the web page would know that you have listened. Showing the other person that you have listened is the most important thing accomplished by backtracking. It also buys you a little time to consider what question you may want to ask next or what direction to take the interaction.
The most important element in backtracking is to keep it in that person's words. Words are symbols that represent experience and have personal meaning. If you change someone's words you run the risk of them thinking that what you said is not what they meant. Be careful of this especially if they are upset.
How much backtracking you do depends on how someone is acting. If the person you are dealing with is being a Tank you do just a little bit of backtracking. Two to three sentences at the most. The Tank has a short attention span. If you are dealing with a Know it All, then you have to do a lot of backtracking.
Ok, I got it. Let's go back.