The type of files used and provided by websites can vary based on mission requirements, but the basic rule should be to not require the user to have addition plugins or software on their devices.
As a best practice the following file type are recommended for general information:
- Portable Document Format (PDF) – All modern browsers have a PDF viewer built in and do not require additional plugins or programs. Must be accessible.
- Video – To maximize compatibility with the greatest number of devices, video should be in the MP4 format. Videos hosted in YouTube can be uploaded in any supported format and will be converted automatically. Requires captions and ideally audio descriptions and transcript (refer to the Video, Audio, and Multimedia standards).
- Audio – To maximize compatibility with the greatest number of devices, audio should be in the MP3 format. Requires transcript (refer to Accessibility standards).
- Photographs – Photographs should use the Joint Photographic Experts Group (jpeg or jpg) format. Requires alt text (refer to Accessibility standards).
- Graphics – non-photographic images should be in the format that compresses as much as possible without losing fidelity. Typically this is Portable Network Graphic (png) format, but could be jpg. Scalable Vector Graphics (svg) can be used but may require special coding. Requires alt text (refer to Accessibility standards).