Source files are the files containing the original, editable version of a digital resource, from which a distribution format suitable for end use can be created. File formats may be based on open or closed standards. It is a component of digital preservation strategies. Their availability, alongside modification rights conferred by open licenses, is a consideration in open practices.

Portable Document Format (PDF) is one of the most common final formats for documents, which can be created from a variety of source files such as word processor formats (ODT, DOCX), presentation formats (PPTX, ODP), or markup languages (Markdown, LaTeX).^{[1][2][3][4][5][6]} These source files, used to author and edit the content, are then converted to PDF for consistent display and distribution across different systems.

In graphic design, source files such as SVG or PSD preserve layers that can be independently manipulated using graphics software.^[7][8][9] From these source files, compressed distribution formats such as PNG or JPEG are derived.

In the context of software development, a source file is a human readable file containing source code written in a programming language.^[10][11] The source file must be processed by a compiler to create a format that can be directly executed or an intermediate form that can be interpreted at runtime.

In hardware design, source files include CAD files for mechanical components and schematics or PCB layout files for electronic components. From these editable source files, manufacturing outputs such as STL files for 3D printing or Gerber files for circuit board fabrication are created.^[12][13][14]

In typography, font source files such as UFO, VFC or .glyphs contain human-readable glyph outlines manipulated using a font editor, from which font binary files such as OTF, TTF, or WOFF are generated.^[15][16][17] These binary files are then used by applications such as word processors to render and format text.

• Media^[18][19]

Source files may use an open file format based on an open standard or a proprietary file format.^{[citation needed]}

In professional practice, ownership of source files may be subject to dispute — designers typically retain them as intellectual property unless contractual terms specify otherwise.^[20]

In digital preservation, retaining source files alongside final-state files is recommended practice to ensure long-term reusability.^[21] Source files retain all original data, and open file formats can support long-term accessibility and reuse of digital resources — proprietary formats may become obsolete, discontinued, or inaccessible.^[22]

The UNESCO 2019 Recommendation on Open educational resources recommends that Member States develop mechanisms to incentivize stakeholders to publish source files using open file formats in public repositories.^[23] It is common for Open Educational Resources such as open textbooks to be available only in a final format such as PDF, limiting the ability of users to modify them despite the rights provided by open licenses.^[24][25][26] The Definition of Free Cultural Works identifies the availability of source files alongside licences as a condition to guarantee freedom to use, study, modify and distribute digital resources.^[27]