E-book reader (e-book device) is a tool for browsing e-books. The size of the screen determines the number of words that can be displayed on a single screen. The technologies applied to the screen of e-book readers include electronic paper technology, LCD and other display technologies.

PPT is a presentation file. Users can make presentations on projectors or computers, or they can print them out and make them into films, so they can be used in a wider range of fields.

Document (foreign abbreviation: DOC, foreign full name: document) is a common file extension of computer files, and now it is mostly: docx. Originally used as a plain text file, this format is more common in different operating systems. Instructions for the use of software and hardware.

TXT file is a text file of computer notepad, and it is one of the files often used in computers.

Pdf (short for portable document format, meaning "portable document format") is a file format developed by Adobe Systems in 1993 for file exchange.