The Amazon Kindle uses a propriety file format that can’t be read by other popular programs and word processors unless the files are first converted to a supported format. Fortunately, there are programs, such as Caliber, that are built specifically for jobs such as these. Calibre allows you to open and view a wide range of eBook formats as well as convert between those formats.
Calibre supports conversion from many input formats to a similarly wide range of output formats.
Supported input formats include: CBZ, CBR, CBC, CHM, EPUB, FB2, HTML, LIT, LRF, MOBI, ODT, PDB, PDF, PML, PRC^, RB, RTF, TCR, TXT
Supported output formats include: EPUB, FB2, LIT, LRF, MOBI, OEB, PDB, PDF, PML, RB, RTF, TCR, TXT.