Comprising of nine states, EU9 has grown to be an integral part of the EU. This group became part of the EU in its 3rd enlargement phase in 2004, injecting new ideas and cultural diversity into the EU society.

The EU9 nations include Hungary, Slovenia, Latvia, Lithuania, Poland, Estonia, Slovakia, Czech Republic, and Malta. These countries have produced meaningful inputs towards furthering the aims of the European Union.

Therefore, grasping the role EU9 plays in the European Union is important for any study relating to international relations, politics, or European economics.

Ever since their inclusion, the members of EU9 have contributed significantly towards shaping the policies of the European Union. Their geographical location provides important strategic benefits, rendering them a vital part of the EU's defense and security strategies.

Additionally, these states have significantly contributed to the website European Union's economic and financial strength. The EU9's rapid economic growth and keen integration into the European market has resulted in amplified trade with other EU countries.

The social contribution of the EU9 is also significant. These countries bring rich historical backgrounds, distinct cultural practices, and varied languages, thereby enhancing the plurality of the EU.

The addition of EU9 has also influenced the political dynamics within the EU. With their involvement, the power dynamics have changed, with new coalitions and alliances forming.

In conclusion, the roles played by the EU9 members are considerable. From economic influence to cultural richness, and from security strategies to political dynamics, EU9 has strengthened the European Union's structure. As such, an comprehensive understanding of the EU9 is crucial to fully grasping the details of the European Union.