<p><strong>Open Source Day</strong> is an international conference gathering fans of open solutions from <ahref="https://en.wikipedia.org/wiki/Central_and_Eastern_Europe"title="Central and Eastern Europe">Central and Eastern Europe</a>. Mission of the event is to introduce <ahref="https://en.wikipedia.org/wiki/Open_source"title="Open source"class="mw-redirect">open source</a> solutions to Polish public and business institutions and popularize it as a secure, efficient, cost saving alternative to proprietary software.<supid="cite_ref-1"class="reference"><ahref="https://en.wikipedia.org/wiki/Open_Source_Day#cite_note-1">[1]</a></sup> The conference has taken place in <ahref="https://en.wikipedia.org/wiki/Warsaw"title="Warsaw">Warsaw</a> since its beginning in 2007. Participants are mainly managers, developers, technical officers of public, banking, and insurance industries.</p><p>The conference has become a platform for exchanging experience, contacts and use cases of open source solutions in fields of: <ahref="https://en.wikipedia.org/wiki/Virtualization"title="Virtualization">virtualization</a>, <ahref="https://en.wikipedia.org/wiki/Cloud_computing"title="Cloud computing">cloud computing</a>, <ahref="https://en.wikipedia.org/wiki/Database"title="Database">database</a>, <ahref="https://en.wikipedia.org/wiki/Big_data"title="Big data">big data</a>, <ahref="https://en.wikipedia.org/wiki/Information_security"title="Information security">Information security</a>.</p>