The content of your website is managed by separate content modules/web applications. The ImpressCMS core is tasked with providing the general content framework so all modules can take advantage of it. The responsibility to cater to specific needs is taken on by the addon modules.
Simply install the module which has the features you need: a news module, forum module, photo album module, there are many third party modules to choose from.
ImpressCMS modules are mostly self-contained, so in order to use one, we will not force you to download an entire scala of technical parts with potentially conflicting versions. In most cases, you just setup the module on your system, configure it the way you want, and that's it.
Upgrades to new versions of modules are done using the 'upgrade' function, which means you can update from an older version and still keep your data. You can launch an update from the Administration Control Panel (ACP)