The EU Blue Card is sometimes compared to the US Green Card. Blue is called the color of the flag of the European Union, so the map must be blue. Its purpose is to grant work and residence permits to citizens of countries outside the EU/EEA. It gives people the right to integrate into the socio-economic landscape and embark on the path leading to permanent residence in Europe. Simply put, people can live and work in Europe without restrictions with a blue card. http://www.confiduss.com/en/info/blog/article/eu-blue-card-acquisition/