E-books and e-books have many formats. The following are some popular and common e-book file formats. 1.Exe file format This is the e-book file format favored by many people at present, and the tools for making this format are also the most. Its biggest feature is easy to read and simple to make. The produced e-book is quite beautiful and can be read without special reader support. E-books in this format have low requirements for the running environment. However, this format of e-books also has some shortcomings. For example, EXE files produced by most related production software do not support Flash, Java and common audio and video files, and need the support of IE browser. 2.CHM file format CHM file format is a help file system based on HTML file characteristics introduced by Microsoft 1998, which is used to replace the previous WinHelp system. In Windows 98, CHM type files are called "compiled HTML help files". The JavaScript, VBScript, ActiveX, Java Applet, Flash, common graphic files (GIF, JPEG, PNG) and audio and video files (MID, WAV, AVI) supported by IE browser are also supported by CHM, and can be linked to the Internet through URL. The disadvantage of this format of e-books is that the user's operating system must be Windows 98 or NT or above. If the operating system of the reader is still Windows 95, you need to install an upgrade package called CHM file reading. 3.HLP file format HLP file format is a help file system used by early operating systems. This format does not require much for the reader's operating system, and Windows 95 and later versions can run. At present, the help files of many software running on Windows platform are almost in HLP format. Of course, with the introduction of Microsoft CHM help file system and the development of operating system, HLP file format is likely to be replaced by CHM. The disadvantage of HLP file format is that it is not beautiful enough. Because many people now put forward higher requirements for the aesthetics of e-books, e-books in this format are not very popular on the Internet at present. But what is certain is that this format of e-books is simple to make and easy to obtain, and has no special requirements for readers. In addition, many software help files are still using this format, so this format will not quit the historical stage in a short time. 4.PDF file format (/)PDF file format is an electronic reading file format developed by Adobe Company of the United States. This file format e-book needs the company's PDF file reader Adobe Acrobat Reader to read, so readers are required to install this reader on their computers. This reader is completely free and can be downloaded from Adobe's website. The advantages of PDF are beautiful appearance, convenient browsing and high security. However, this format does not support various HTML-based technologies such as CSS, Flash, Java and JavaScript, and is only suitable for browsing static e-books. E-books in PDF format can be made and edited by Adobe Acrobat, and the latest version is 4.0. 5.WDL file format (/)CEB is a Chinese e-book, which is a completely high-fidelity Chinese e-book format. The format used by Founder Apabi Reader, a brand-new e-book reading tool developed by Founder Electronics Co., Ltd. of Peking University, can keep all the information of the original document, including pictures, numerical formulas, chemical formulas, tables, chess and cards, music scores, etc. At the same time, this format compresses characters and images well, and the amount of file data is small. 12. CAJ file format (ki.net/) (CAJ for short) was edited and produced by the editorial department of academic electronic publications of Tsinghua University National Engineering Research Center for Optical Disc and Beijing Tsinghua Information System Engineering Company. For readers, after finding a specific article, they can visit the full-text database of China Journal Network and download the corresponding CAJ file. You can use CAJ file reader CAJViewer to read and print CAJ files obtained through "full-text database" locally. 13.PDG file format (/) Beijing Century Superstar Company has its own digital technology (PDG) and special reading software-Superstar Book SSReader, which has formed a complete digital library solution. It has been successfully applied to more than 500 units at home and abroad, such as Central Archives, Zhongshan Library, Shenzhen Library, PLA Medical Library, Wenzhou Library and University of California, San Diego Library. It has become one of the basic modes of digital library construction in China and even the whole world. 14. E-book format of National Library. It compresses the scanned book image into a very small NLC file according to JBIG standard. NLC file is a variant of JBIG format. You can use the software Book Reader for NLC to read, and because most e-books in this format can't get text and image data directly.