• Categories help you organize material in groups
• Where is Search : Categories?
• Use Add in the contents window to place an item in the knowledge tree
• Branch selection does not affect the template used
• Searching a category
• You can make repetitions on elements belonging to a given branch
• You can make SuperMemo apply category template on moving an element to a category
• Deleting category does not delete its elements
• You can rehearse only those elements that belong to a selected category
• Each category has its own hook
• Task Extract adds elements as children of the article (not the current tasklist)
• Are Categories treated distinctively in learning?

See also:

• Using templates and categories
• FAQ: Templates
• FAQ: Collection authoring

Categories help you organize material in groups
Question:
What is the purpose of the category registry (Search : Categories)?
Answer:
SuperMemo introduces the concept of a category to help you keep items related to different subjects in different branches of the knowledge tree (contents window). It also makes it possible to give different element groups different appearance (e.g. size of text components, screen layout, font, color, and many more). Read more: Using categories

Branch selection does not affect the template used
(Vidar Garlie, Norway, Mar 18, 1999)
Question:
When I go to the contents window, select a category branch and press Alt+A, the template of this category is not used! Can you help?
Answer:
To use a category template, you have to first choose the category in the category combo box on the Tools toolbar. Selecting branches in the contents window does not affect the current category selection

Deleting category does not delete its elements
(Luis Gustavo, Brazil, Oct 1, 2000)
Question:
If I delete a category, will all its elements be deleted?
Answer:
No. The category is an abstract structure living above the level of the knowledge tree. Once you delete it, no elements will be affected. Nor will the structure of the knowledge tree. To delete the section of the knowledge tree belonging to a category, select the root branch in the contents window and press Del

Task Extract adds elements as children of the article (not the current tasklist) 
Question:
When I use Task Extract it adds tasks to a wrong branch in the contents window
Answer:
Task Extract adds tasks to the current branch which may differ from the branch in which the current tasklist is located. This satisfies the principle of incremental reading in which all extracts and clozes generated from an article initially become descendants of the article 

Use Add in the contents window to place an item in the knowledge tree
(R.K., Sun, Jun 17, 2001 17:54)
Question:
I would expect SuperMemo to add a new item as a straight neighbor of the previously added element in the contents window. Why isn't it so?
Answer:
Selection in the contents window is too transient to be the basis of choosing the insertion point for new material with Add new (Alt+A). This would require constant user attention as to the present selection. As a remedy, the concept of a category has been introduced. Each category, such as biology or geography, has its own insertion point called a hook. Now, all you have to do is to select a category, and Add new will add new elements to that category. Added elements will be listed sequentially as neighbors. However, if you would like to add new items to the location determined by the selection in the contents window, use Add in the contents window instead

Where is Search : Categories?
(Serguei Koureda, Sunday, October 20, 2002 11:08 PM)
Question:
Why is there no option Categories in Search menu?
Answer:
You need to be in the Professional level (File : Level) and you need full access on (Tools : Options : Access). If you use different levels and mode settings, some menu options may be turned off

Searching a category
(Maarten Mols, Mon Feb 17, 2003 4:23 am)
Question:
How can I limit Search : Find Elements to a certain category?
Answer:

1. Go to the root of the category (in the contents window) 
2. Choose Search Branch (Ctrl+F) 

or 

1. Search for the term 
2. In the search browser choose Child : Branch (and select category root) 

or 

1. Open the category in the browser (View : Branch in the contents window on the category root)
2. Choose Search All (Ctrl+S)

You can make repetitions on elements belonging to a given branch
(louis_lheureux, Canada, Monday, November 18, 2002 11:22 PM)
Question:
Is there a way to make a given category the default category for learning each time I press the Learn button?
Answer:
No. However, you can select a given branch in the contents window and make repetitions only on elements that belong to this branch. To make repetitions only in a given branch:
(1) Press the Contents button (Alt+C) to switch to the contents window,
(2) In the contents window, select a branch, in which you would like to make repetitions,
(3) Press the Learn button (Ctrl+Alt+L) to start repetitions on elements that belong to the selected branch

You can rehearse only those elements that belong to a selected category
(louis_lheureux, Canada, Monday, November 18, 2002 11:22 PM)
Question:
In my daily random repetitions of the outstanding material, I have stumbled against an element that belongs to my History category. Is there a quick way to make repetitions on the rest of elements belonging to this category?
Answer:
Once you see any element that belongs to a given category, right-click your mouse and then choose Learning : Learn branch (Ctrl+Alt+L) from the element menu

Each category has its own hook
(Ahmet, Tuesday, December 10, 2002 9:07 PM)
Question:
Could you please introduce a shortcut key for the Set hook command available in the contents menu as I add a lot of new elements and have to use it each time a given element is from different discipline?
Answer:
You do not need to set a hook for a given category each time you would like to add new elements to it. When you create categories, each category has by default its own hook, which is usually the root node of a given category. If you would like to add elements to a different category, you change the active category to the one, to which you would like to add new elements. You can change the active category by selecting it from the category combo box in the Tools toolbar (Ctrl+Alt+C). For a thorough discussion of categories, read: Using categories

You can make SuperMemo automatically apply category template when moving an element to a category
(Anatoliy Lipatov, Ukraine, Friday, January 10, 2003 8:59 AM)
Question:
Each time I create an extract SuperMemo asks me the following question: 
"Apply category template? 
Template=Classic."  
Is there an option to turn it off?
Answer:
(1) Choose Search : Categories in the main menu to open the category registry,
(2) In the left pane, click a category, for which you would not like SuperMemo not to ask this question,
(3) In the top-right pane, click the Auto-Apply checkbox until it is checked and not grayed

Are Categories treated distinctively in learning?
(anonymous, Jul 22, 2010, 16:10:40)
Question:
I was wondering if Categories are treated differently concerning the scheduling of the items, since different subjects hold different levels of difficulty.
Answer:
Items belonging to different categories are treated in the same way. The only difference is that you can define a default forgetting index for the entire category. New items added to a modified category will have a distinctive forgetting index. This way they can be reviewed more often, or less often, and they can be remembered better, or worse, depending on the setting.