Books that can be obtained via the Internet can be designed to be read using a variety of software. Just imagine: what would the interlocutor think of you twenty years ago, if you asked him, what would be more convenient to read the book? And today this issue is very relevant due to the abundance of e-book formats. The most commonly used formats are DjVu, FB2, PDF, CHM, DOC, RTF, TXT.
To read books in DjVu format, you can use, for example, the free utility WinDjView - http://windjview.sourceforge.net/ru. There is also an option for working on MacOS. This format is specially designed for storing scanned documents, the contents of which are difficult for text recognition - manuscripts, journals, scientific literature with a large number of formulas, etc. It is also used for the most accurate transfer of historical and archival documents, in which, in addition to the text, individual design features are important - paper texture, corrections made, ink prints, etc. In addition to an image, a DjVu file can contain a text layer and hyperlinks. The format allows you to start reading even before the file transferred over the network is fully loaded
To read books in FB2 (FictionBook) format, you can use, for example, the FBReader program - http://www.fbreader.org. This format is based on XML standards and basically only carries information about the text. The appearance in which this information will be presented depends entirely on the settings of the book viewer of this format
For reading books in PDF (Portable Document Format) format, the free Adobe Reader is quite suitable - http://get.adobe.com/reader/otherversions/. This format, developed and actively implemented by Adobe, is primarily used to present printed products in electronic form. It allows you to embed fonts, images, shapes, multimedia elements, etc. into documents
To read books in DOC, RTF, TXT formats, you can use, for example, Microsoft Word. These are text formats of varying degrees of "advancedness" - from simple text without formatting features (TXT) to documents with a complex structure, graphic, multimedia and interactive inserts (DOC).
To read books in CHM (Microsoft Compiled HTML Help) format, no special software is required - such files are opened using standard Windows OS tools. The vast majority of books in this format are various kinds of reference books, consisting of a set of HTML pages and a table of contents with links. Sometimes they have a subject index and information base for full-text search in the content of the pages.
There is also universal software that makes it possible to read e-books in most formats. For example, STDU Viewer, which supports TIFF, PDF, DjVu, XPS, JBIG2, WWF, FB2, TXT, Comic Book Archive (CBR and CBZ), TCR, PalmDoc (PDB), DCX, BMP, PCX, JPEG, GIF, PNG, WMF, EMF, PSD.