Salesforce knowledge and Answers and chatter answer can use Data categories because it helps users to classify and find articles or questions.
Data categories help administration to control access to articles and questions.
There is a five level hierarchy of data categories. Defining Multiple categories help in the classification of articles in the knowledge base.
Classification of articles helps users to find the article they require. For example, if you want to classify articles in two areas like Sales regions and Business units.
It can be easily possible by creating two category groups, Sales Regions and Business units.
A geographical hierarchy can come under the Sales Regions category group, for example, All Sales Regions as the top level, North America, Europe, and Asia at the second level, and so on.
In an answers zone, for simple browsing, Data categories help to compose inquiries.
Each answers zone support one category group. For instance, in case you're a PC maker you may make a Products category group that has four sibling categories: Performance Laptops, Portable Laptops, Gaming Desktops, and Enterprise Desktops.
On the Answers tab, zone members can assign one of the four categories to each question and then browse these categories for answers to particular questions.
Benefits of Data Categories
Logical Classification of Articles
If you are a knowledge base administrator, you can easily organize your knowledge base articles into a logical hierarchy and
tag articles with the attributes that are relevant to your business.
Easy Access to Questions
If you are an answers administrator, you can choose which data categories are visible on the Answers tab.
If Zone members can tag a question with a category as questions with a category
help finding questions and answers easier for other members.
Control of Article and Question Visibility
If you are a knowledge base or answers community administrator, you can centrally control the visibility of articles or questions by mapping roles,
permission sets, or profiles to categories in the category groups.
The users with visibility can automatically see the categorized article or question.
Article Filtering
If articles are classified into logical categories, then a support agent can
rapidly and effortlessly find the article required by filtering the organization’s knowledge base.
Filtering by category has expansive results that include a category's upward and downward relatives in the category hierarchy to ensure support agent see all relevant articles.
For example, if your category hierarchy for products has the levels All Products > Computers > Laptops > Gaming Laptops
and you are helping a customer with a laptop problem, filtering by Laptops returns articles classified with Laptops as well as
articles classified with Computers, All Products, or Gaming Laptops.
Effectively, you are made aware of helpful related articles like a free sending offer for all items or an upgrade offer for gaming portable laptops.
(To prevent irrelevant results, category filtering doesn't return non lineal relatives like siblings and cousins.
Articles about Desktops, a sibling of Laptops, would not display.)
Article and Question Navigation
If you are an end user, you can navigate the categories on the Articles tab or Answers tab to find the information you need to solve your problem.
Managing Category Groups for Articles and Questions
If your organization has Salesforce Knowledge and an answers community, you can create separate category groups
or use the same category group for articles and questions.
Category groups can be used by Salesforce Knowledge (articles) or answers communities (questions).
In both cases, category groups are containers for individual data categories.
To create or edit a category group:
1. From Setup, click Customize | Data Categories.
2. To create a new category group, click Create New in the Category Groups section.
By default, you can create a maximum of five category groups and three active category groups.
Contact Salesforce to request additional category groups.
To edit an existing category group, hover your cursor over the category group name and then click the Edit Category Group icon (Edit Category Group).
3. Specify the Group Name. This name appears as the title of the category drop-down menu on the Article Management
and Articles tabs, and, if applicable, in the public knowledge base.
The Group Name does not appear on the Answers tab.
4. Optionally, modify the Group Unique Name. This is a unique name used to identify the category group in the SOAP API.
5. Optionally, enter a description of the category group.
6. Click Save. You receive an email after the save process completes.
You can now add categories to your category group.
When you create a new category group, Salesforce automatically creates a top-level category in the group named All.
Optionally, double-click All to rename it.