You can also install Pale Moon from one of these fully-endorsed third-party repositories:
Repositories for Debian and Ubuntu -- Maintained by Steve Pusser
That's "Stevo" from the Mepis/MX community. In the past, I've installed Pale Moon by downloading the .tar.bz2 file from the Pale Moon for Linux page at Sourceforge. Seemed like a good idea to try Stevo's repos this time around, so I followed the provided link, selected Debian, and followed the steps for "Debian 8.0". Here's Pale Moon in Jessie GNOME, customized a little bit to suit my tastes:
This approach puts a palemoon.list file in /etc/apt/sources.list.d/, containing the following line:
deb http://download.opensuse.org/repositories/home:/stevenpusser/Debian_8.0/ /
So, updates should be available via Synaptic.
Folks are voting for their "preferred web browser" in this week's DistroWatch Weekly Opinion Poll. Note that Pale Moon is not listed among the voting options, but folks have been posting positive comments about Pale Moon in the comments section, and that's what prompted me to take the browser for another spin (I haven't used it in maybe a year or two).
Pale Moon is a nice alternative to Firefox, especially for folks running on low-spec hardware. Website: http://www.palemoon.org/