Amazon's Kindle readers support a variety of e-book formats, including MOBI, AZW, KF8/AZW3 and PRC. MOBI came from Mobipocket, which Amazon acquired in 2005, and files may use the MOBI or PRC extension. MOBI is also widely used without copy protection in online libraries where free e-books are available. AZW is a copy-protected version of MOBI, and both AZW and MOBI are Amazon proprietary formats.The latest and most advanced format is KF8 (Kindle Fire 8), also known as AZW3. KF8 supports HTML5 and CSS3, which are Web standards that provide advanced font and layout formatting.Third-party software such as Calibre, pronounced "Cal-ih-bur" (www.calibre-ebook.com), is used to convert EPUB and other e-book formats to Kindle formats. See Kindle.