> ## Documentation Index > Fetch the complete documentation index at: https://docs.pixldata.com/llms.txt > Use this file to discover all available pages before exploring further. # Polygon > The Polygon Tool is used for high-precision instance and semantic segmentation. It allows for the annotation of complex or irregular shapes that cannot be accurately captured by standard bounding boxes. Polygon Tool 1 ### **Getting Started** * **Tool Selection:** The Polygon Tool is selected via the **Smart Tool Palette**. * **Efficiency (Tool Persistence):** To speed up the workflow, the last selected tool remains active by default. There is no need to re-select the Polygon Tool after completing a shape; the user can immediately begin drawing the next object. * **Closing a Shape:** A polygon can be finalized in two ways: 1. Clicking back on the **starting point** (the first node). 2. Pressing the **Enter** key to automatically close the shape from the last point to the first. ### **Interactive Toolbar: Polygon Modes** When the Polygon Tool is active, the **Interactive Toolbar** provides four specialized modes to handle overlapping shapes and complex geometries. These modes allow users to manage how new polygons interact with existing ones: 1. **Overwrite:** The default mode. New polygons are drawn independently, regardless of existing annotations. 2. **Subtract:** Used to cut out a section from an existing polygon. This is ideal for creating "holes" or removing specific parts from a larger shape (e.g., labeling a donut shape). 3. **Auto Subtract:** A smart mode that automatically trims the new polygon so it does not overlap with existing shapes, ensuring perfectly aligned boundaries without manual effort. 4. **Union:** Allows for the merging of two or more polygons. When used, the new shape is combined with a selected existing polygon to form a single, unified logical entity. ### **Precision & Speed** The tool is optimized for high-speed vertex placement. Whether defining a simple triangle or a complex 100-point boundary, the canvas remains responsive, allowing for professional-grade segmentation at scale.