Canonical has decided to keep Mozilla Firefox as the default web browser on Ubuntu 13.10 Saucy Salamander and not switch to Chromium (as it was once said), Google’s open-source alternative of Chrome.
At first, the developers proposed to use Chromium as default, because it has better Unity integration, but changed their mind and confirmed that they will keep Firefox until Ubuntu 14.04 will be released. Firefox is a very popular among the Linux users, coming already preinstalled on Fedora, OpenSUSE, Linux Mint and others.
Also, the Lubuntu team has announced a few weeks ago that they will replace Chromium with Mozilla Firefox, as the default internet browser, on Lubuntu 13.10 Saucy Salamander.