I normally tend to use the PPAs (Personal Package Archives) found in launchpad.net, but I have noticed more and more that some repositories are being created in other places or a website that manages packages in a similar fashion like launchpad.
So my questions are:
What is an official repository and an unofficial one (Local Repository), including the ones created outside of Launchpad.
How do repositories created outside of Launchpad compare to the ones found inside of it in terms of first, security, followed by any other features that both offer.
How do official software repositories differ from the ones created by 3rd party PPAs in Launchpad or outside of it.