Text only (txt) – universal format, small informational volume, but text formatting results are not saved.
Extended text format (rtf) is a universal format, a large amount of information, but the results of text formatting are preserved.
Word document (doc) is a universal format that fully preserves formatting.
OpenDocument Format (ODF) is an open document format for office applications. Web page (htm or html) – a universal format, used to store web pages, a small amount of information, but formatting is preserved.
Portable Documents (pdf) is a format used to reliably present and exchange documents, regardless of software, hardware or operating system.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.