bpy

bpy is Blender's Python API module that exposes Blender's data, operators, and UI for scripting and automation. It is the primary interface for extending Blender with Python, enabling users to create tools, automate repetitive tasks, and build add-ons. Scripts typically run in Blender's embedded Python interpreter and can interact with most Blender features, including scenes, objects, materials, animation, rendering, and user interface elements.

The API is organized into several submodules: bpy.data provides access to data blocks such as objects, meshes, materials, textures; bpy.context exposes the current context (active object, selected objects, current mode); bpy.ops contains operators that perform actions (such as object transformations, creation, file I/O); bpy.types contains Python classes that wrap Blender data types; bpy.props defines properties for custom data blocks; bpy.utils and bpy.app supply utilities and runtime information.

Scripts can be run from the Blender Text Editor, loaded from external files, or packaged as add-ons. Changes made through bpy affect the current project and can be saved to a .blend file or exported. Since calls often depend on context, scripts must check the active context before performing certain operations.

Common uses include automating repetitive editing, batch exporting, procedural content generation, rigging and animation tools, scene setup, and add-on development. Developers create operators and panels, register classes, and define preferences and properties so the tool integrates with Blender's interface.

Version compatibility is important: Blender's Python API evolves between releases, so scripts target a specific Blender version; the official API reference documents available modules, properties, and operator signatures. Performance considerations include avoiding unnecessary context switches and using data-block references to manage memory.