Docview

Docview is the document viewer within Emacs. Use this library to view non-text files like pdf, odt etc without leaving Emacs. It works by converting a file to an image and then displaying the image in an Emacs buffer.

[C-x C-f] myfile.pdf

This should display the pdf file. On GNU/Linux systems, this works out of the box. If this command doesn't work, install or configure the various programs under M-x customize-group RET doc-view RET.

[C-c C-c] (or M-x image-toggle-display)

When in Docview-mode, this will toggle between text format and it's image representation. This can be useful for directly modifying PDF files, for instance.