For long-term storage and use over long periods of time, "open" formats that can be read, opened and used without restriction are particularly suitable.

Format recommendations for long-term archiving

File format	To prefer	To avoid
Table	CSV, TSV, SPSS portable, XLSX	XLS
Text	TXT, HTML, RTF, PDF/A, DOCX	DOC, PPT, PDF
Multimedia	Container: MPEG4, MKV Codec: Theora, Dirac, FLAC	QuickTime, Flash
Images	TIFF, JPEG2000, PNG	GIF, JPG

(from Dolzycka, Dominika, Biernacka, Katarzyna, Helbig, Kerstin, & Buchholz, Petra. (2019). Train-the-Trainer Konzept zum Thema Forschungsdatenmanagement (Version 2.0). Zenodo. http://doi.org/10.5281/zenodo.2581292 , p. 84)

Further information: Data Formats for Preservation on openaire.eu and Formate erhalten (German only) on forschungsdaten.info.