> For the complete documentation index, see [llms.txt](https://docs.annolab.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.annolab.ai/projects-directories-and-sources.md).

# Projects, Directories, and Sources

- [Projects](https://docs.annolab.ai/projects-directories-and-sources/projects.md): Projects are the highest level abstraction in the Annotation Lab platform. They contain directories, source files, schemas, and annotation layers. They are also the scope at which work can be shared.
- [Directories](https://docs.annolab.ai/projects-directories-and-sources/directories.md): Directories are containers for Source Files that can be used to help organize the contents of a project
- [Source Files](https://docs.annolab.ai/projects-directories-and-sources/source-files.md): Source files are files that contain things you want to annotate or run models on. Currently we support PDF and .txt file formats
- [Upload Sources](https://docs.annolab.ai/projects-directories-and-sources/upload-sources.md): Upload PDF source files using a three-step process: initialize an upload, PUT the file to a signed URL, then confirm creation and start processing.