The Script is designed to work on Windows or Mac machines too.
If you right click on the icon you see all the functions available, including what I think is a sensible default, Show Updates.
All the package managers share the same list and the same list of repositories but each one presents the information slightly differently.
The main time you will need to update the lists is when/if you have made changes to the list of software channels or if you have made changes to Synaptic's configuration.
You can install, remove, configure, or upgrade software packages, browse, sort and search the list of available software packages, manage repositories, or upgrade the whole system.
You can queue up a number of actions before you execute them.
Synaptic will inform you about dependencies (additional packages required by the software package you have chosen) as well as conflicts with other packages that are already installed on your system.
Synaptic's sibling on the Kubuntu desktop is Adept.
There is a new program called gnome-app-install that shows a simple list of common GNOME programs with a checkbox for installation or removal.
Also it is up to the team developing a release to make sure that the repositories have plenty of the right sort of packages to meet people's needs. Companies need to get their product onto shelves and shops need to show they have plenty to sell.
This saves individual users from having to identify the 'correct' website for a product and assess whether or not the site has been compromised and whether they are getting a genuine product or something stuffed full of malware.
The standard repositories are all free as are the Medibuntu repositories and most others that are easily found and added.
Theoretically there is nothing stopping a games manufacturer (for example) setting up a one-off or monthly charge for accessing a specialist repository.
The main window is divided into three sections: a package browser on the left, the package list on the upper right, and package details on the lower right.