Marie Kondo provides consulting advices to people who need to de-clutter their homes. This book shows you how to discard items and then the storing methods for those items you love to keep.
To de-clutter is to create space in your living environment. It is magical because the outcome is living happily. According to the author, it is life-changing after going through the process. You would be able to find things in the home and these items give you joy when you use them. Things are placed in specific locations as a matter of habit. Because items not discarded are items that spark joy, you would be happier using them or wearing them.
For me, this book affirms what we have been doing right in reducing clutter in our home. My first advice is not to buy thing unless it is really required. Buy only things you would love to use. That is the starting point. The book would be useful when you have already accumulated a lot of things and your home is appearing cluttered.