Oskari is updated every now and then (approximately once in every 2-4 months) and it is very important to update as soon as possible, since the new version is always the best, most reliable and secure.
Release notes can be found from GitHub. Notice that you can view all previous release notes from the same page. Release notes will be posted to the audience also through the Oskari user email list, so go ahead and join the list so you know when to update. New releases are informed also via social media in Twitter and Gitter.
How to change versions?
Read how to upgrade Oskari versions, remember to upgrade database schema as well.