Short bio: Computer Scientist, FOSS supporter (read more)
Tux Machines (TM)-specific
With the release of Ubuntu 9.10 late last year Canonical introduced PPAs, which is short for Personal Package Archives. A PPA allows anyone that has signed the Ubuntu Code of Conduct to easily distribute software they have packaged to Ubuntu users. This revolutionary idea allows those who do not have the capability to establish their own repository to easily provide package updates to their users. Want the latest version of Openshot or PiTiVi? Then simply add a PPA to your system that packages up to date versions of these softwares and you will be set to go!
The problem with this system you ask? There is namely one issue: Canonical does not review any of the packages that are uploaded to PPAs. Because of this adding software from various PPAs wily nilly in reality is more dangerous than installing software on Windows.