Chromium is a browser similar to Google Chrome and uses the same code base. Chromium however does not include automatic updates, has fewer audio and video codecs, and no Flash capability. Advantages over Google Chrome include smaller size and resource usage, fewer tie-ins with Google, open source, and generally better privacy.
Chromium is cross-platform with clients available for Mac, Linux, and ChromiumOS. X-Chromium is a wrapper program, available in 32 and 64-bit versions.