> ## Documentation Index > Fetch the complete documentation index at: https://docs.abbyy.com/llms.txt > Use this file to discover all available pages before exploring further. # Create a derived skill in Advanced Designer > Create a derived skill in Advanced Designer to inherit fields and rules from a base skill while allowing customization. You can create a [derived skill](/vantage/documentation/advanced-designer/document-skills/derived) from any skill in the **Skill Catalog**, including built-in and read-only skills. To create a derived skill, do one of the following: * Select a skill in the **Skill Catalog** and click the derive skill icon. * Double-click the name of a skill in the **Skill Catalog** and in the dialog box that opens, click **Create and Edit Derived Skill**. To see the base skill of a derived skill, click the settings button next to the name of the derived skill. ## Base skill activity When a derived skill is created, an activity referencing its base skill is added at the beginning of the document processing flow. This activity is named `Base: ` and cannot be edited or deleted. To test other activities in isolation, exclude the `Base: ` activity from the document processing flow by redirecting its incoming arrow to a different activity. If you're not satisfied with the derived skill after testing, consider creating a custom skill from scratch. ## Fast Learning activity A Fast Learning activity is also added immediately after the `Base: ` activity. You can modify this activity as follows: enable or disable fields, add new fields, or train the activity. If needed, you can delete this activity; in this case, the skill will no longer be trainable. For more information about the Fast Learning activity, see [Setting up a Fast Learning activity](/vantage/documentation/advanced-designer/activities/fast-learning-setup). When updating a derived skill to the new version of its base skill, the Fast Learning activity does not change. This preserves the training results on custom examples in the derived skill. ## Add activities You can also add other activities to the document processing flow at any position before or after the `Base: ` activity. For example, you can add an Address Parsing activity to break down full addresses extracted by the base skill. ## Related topics What derived skills are and when to use them. Customize fields, rules, and text recognition. Update to a new base-skill version.