Books can be classified by the "new favorite" function. The operation is as follows:

1. Open the kindle and click the three vertical points in the upper right corner, as shown below;

2. In the drop-down menu, click and select "New Favorite", as shown below;

3. For example, if you want to classify the history books and create a new "History" folder, click OK, as shown below;

4. In the book interface that pops up automatically, check the box behind the book that you want to put into the history favorites, and click OK. In the same way, create other categories and save books in different favorites.