Adobe reader is the most essential PDF viewer . This guide helps you to install adobe reader in ubuntu 14.04 Desktop. As of now adobe reader is not include
XPDF is an open source viewer for Portable Document Format (PDF) files. (These are also sometimes also called 'Acrobat' files, from the name of Adobe's PDF software.) The Xpdf project also includes a PDF text extractor, PDF-to-PostScript converter, and various other utilities.
Xpdf runs under the X Window System on UNIX, VMS, and OS/2. The non-X components (pdftops, pdftotext, etc.) also run on Win32 systems
requiers 50mb - Light enough to power a 486DX with 16MB of Ram
APPS: XMMS (MP3, CD Music, and MPEG), FTP client, FireFox, spreadsheet, Sylpheed email, word-processor (Ted), three editors, graphics editing and viewing , PDF Viewer, file manager, chat, VNCviwer, Rdesktop, SSH/SCP server and client, DHCP client, PPP, PPPoE (ADSL), a web server, calculator, NFS, Fluxbox and JWM window managers, games, system monitoring apps, a host of command line tools, USB support, and pcmcia support, some wireless support
Okular combines the excellent functionalities of KPDF with the versatility of supporting different kind of documents, like PDF, Postscript, DjVu, CHM, and others.