Octopress is a framework designed for Jekyll, the static blogging engine powering Github Pages. So what is Jekyll?
{% blockquote Jekyll Wiki https://github.com/mojombo/jekyll/wiki/Usage %}
Jekyll at its core is a text transformation engine. The concept behind the system is this: you give it text written in your favorite markup language, be that Markdown, Textile, or just plain HTML, and it churns that through a layout or series of layout files. Throughout that process you can tweak how you want the site URLs to look, what data gets displayed on the layout and more.
