> For the complete documentation index, see [llms.txt](https://docs.pgecom.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.pgecom.com/api-endpoint/ecommerce/invoice.md). # Invoice Categories serve as a fundamental organizational tool, enabling you to systematically classify and present your products to users. This feature empowers you to create distinct groupings based on common themes, characteristics, or attributes, offering a structured and intuitive way for customers to navigate through your diverse product range. Through the strategic implementation of categories, you can enhance the user's journey by providing a well-defined framework for exploration. Users can easily locate and browse products within specific themes or genres, facilitating a more seamless and personalized shopping experience. By combining the power of categories with collections, you create a comprehensive system that optimizes product discovery, fostering user engagement and satisfaction within your online store. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://docs.pgecom.com/api-endpoint/ecommerce/invoice.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.