Hello Mayuri, 

If you're refering to the XML definition Category tag (like the below example), they simply put your input in a tab with that name, or create a tab if one doesn't exist already.

<property key="amount" type="attribute" required="true">
            <caption>Payment amount</caption>
            <category>Configuration</category>
            <description>Attribute that holds the payment amount.</description>
            <attributeTypes>
                <attributeType name="Long"/>
            </attributeTypes>
        </property>

So in the example I've given a Payment amount option will appear in a configuration tab.

Does that explain the concept?