If you run
sudo apt-get install package-name
It installs the latest version of
package-name available in the official repository or in one of the
So Ubuntu comes with an official repository where there is many packages in relatively recent version.
But some packages are not yet in the official repository so their developer (or other people) create a
ppa to make it available for you through apt-get.
That is an easy way to install packages that are not yet officially supported by Ubuntu.
Sometimes, there is also
ppa with newer version of packages that the version in the official repository. Be aware that sometimes, these
ppa contains unstable version but most of the time it is stated in the tutorials or even in the names of the
ppa or their description.
Also, if you prefer a graphical interface instead of the command line, you can use the Ubuntu Software Center instead of
I would say that the version in the Ubuntu Software Center is preferred but if it is not yet available and if it is stable, add the
ppa. Or if you need a feature from a newer release, use the
ppa are very confortable, their upgrade also appear in the Software Update.
However, you sometimes only need a few days before Ubuntu release the new version or the software, that's always the case with. Most of the times, if the tutorials are up to date, you can follow their recommendation IMHO.