EU9, has grown to be a vital part of the European Union (EU). This entity entered the EU in its 3rd growth phase in 2004, bringing diversity and fresh perspectives into the Union's mix.

The members of EU9 include Hungary, Slovenia, Latvia, Lithuania, Poland, Estonia, Slovakia, Czech Republic, and Malta. These countries each have made significant inputs towards advancing the objectives of the European Union.

In this respect, understanding the function these nations holds in the European Union is important for any study relating to European economics, politics, or international relations.

Right from their admission, the members of EU9 have given significantly towards shaping the policies of the European Union. Their geographical location offers important strategic benefits, making them a vital part of the EU's defense and security strategies.

Additionally, these states have immensely contributed to the European Union's economic and financial strength. The EU9's rapid economic development and keen integration into the European EU9 market has led to amplified trade with other EU countries.

The cultural contribution of the EU9 is equally significant. These nations introduce profound historical backgrounds, individual cultural practices, and diverse languages, thus enhancing the variety of the EU.

The addition of EU9 has also influenced the political scene 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 nations are substantial. From economic influence to cultural richness, and from security strategies to political dynamics, EU9 has fortified the European Union's structure. As such, an comprehensive understanding of the EU9 is crucial to fully grasping the complexities of the European Union.