Open File Formats are file formats that are published and freely available for anyone to use. A file format is a standard way of encoding storage of computer information. Open file formats can be contrasted with proprietary, protected file formats. Open file formats are often recommended for preservation purposes because they typically do not require special software to open.
The JPEG file format is an open file format for images that does not require special licenses to use.
A CSV file is also an open file format that does not require special licenses to use, compared to an XLS file format which requires Microsoft Excel to use.