Below are some examples of the different types of data you might generate during your research, and how best to store them for longevity, usability, openness, and FAIRness.
You may notice that some of the most widely used file formats are not necessarily what we'd recommend as your format of choice.
Ultimately, what file formats you decide to use will depend on the specifics of your research project. XML (.xml) is recommended as an alternative to Microsoft Word (.doc), because Word documents are notoriously difficult for machines to process and interpret (meaning, they are not interoperable). Similarly, in the case of Audio files, FLAC is recommended over the perhaps more common MP3 format, because FLAC is a lossless format, meaning no data is lost when you save it. In the case of images, TIFF is preferable over more common formats such as JPEG for the same reason; TIFF loses less data and is thus more reliable for longterm usability.
You can use multiple formats during a project. For example, data contained in PDF format could be supplemented with content stored in XML.
For more recommendations see:
Recommended formats — UK Data Service
Lossy Compression: Everything You Need to Know | Adobe
File Format Selection - Research Data Management - Research Guides at New York University (nyu.edu)