List of all installed packages

[Marco Kunze <makunze@gmx.de>]

Hi,

This is not really a specific question for laptops, but I hope I can get 
an answer here anyway ;-)

I would like to get a list of all packages installed on a system, 
including their version in order to track the changes that has been made 
during a system upgrade.

Is there any method to achieve this?

Thank you very much,

Marco