Editing Blender (software) (section)

===File format===
Blender features an internal file system that can pack multiple scenes into a single ".blend" file.

* Most of Blender's ".blend" files are forward, backward, and cross-platform compatible with other versions of Blender, with the following exceptions:
** Loading animations stored in post-2.5 files in Blender pre-2.5. This is due to the reworked animation subsystem introduced in Blender 2.5 being inherently incompatible with older versions.
** Loading meshes stored in post 2.63. This is due to the introduction of BMesh, a more versatile mesh format.
** Blender 2.8 ".blend" files are no longer fully backward compatible, causing errors when opened in previous versions.
** Many 3.x ".blend" files are not completely backwards-compatible as well, and may cause errors with previous versions.
* All scenes, objects, [[materials system|materials]], textures, sounds, images, and post-production effects for an entire animation can be packaged and stored in a single ".blend" file. Data loaded from external sources, such as images and sounds, can also be stored externally and referenced through either an absolute or relative file path. Likewise, ".blend" files themselves can also be used as libraries of Blender assets.
* Interface configurations are retained in ".blend" files.

A wide variety of import/export scripts that extend Blender capabilities (accessing the object data via an internal [[Application programming interface|API]]) make it possible to interoperate with other 3D tools.

Blender organizes data as various kinds of "data blocks" (akin to [[glTF]]), such as Objects, Meshes, Lamps, Scenes, Materials, Images, and so on. An object in Blender consists of multiple data blocks&nbsp;– for example, what the user would describe as a polygon mesh consists of at least an Object and a Mesh data block, and usually also a Material and many more, linked together. This allows various data blocks to refer to each other. There may be, for example, multiple Objects that refer to the same Mesh, and making subsequent editing of the shared mesh results in shape changes in all Objects using this Mesh. Objects, meshes, materials, textures, etc. can also be linked to other .blend files, which is what allows the use of .blend files as reusable resource libraries.