Comprising of nine states, EU9 has grown to be a vital component of the European Union (EU). This entity became part of the EU in its 3rd expansion phase in 2004, implanting diversity and fresh perspectives into the grand unity.

The EU9 nations include Poland, Lithuania, Latvia, Hungary, Czech Republic, more info Slovakia, Slovenia, Estonia, and Malta. These states have given meaningful efforts towards furthering the objectives of the European Union.

Therefore, knowing the part EU9 holds in the EU is required for any study relating to international relations, politics, or European economics.

Right from their admission, the members of EU9 have contributed substantially towards shaping the European Union's policies. Their geographical location provides critical strategic benefits, turning them a crucial part of the defense and security strategies of the EU.

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

The social contribution of the EU9 is also significant. These nations bring profound historical backgrounds, unique cultural practices, and varied languages, thereby enhancing the diversity of the EU.

The addition of EU9 has also influenced the political scene within the EU. With their presence, the power dynamics have altered, with new coalitions and alliances developing.

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 robustly augmented the European Union's framework. As such, an in-depth understanding of the EU9 is vital to fully grasping the intricacies of the European Union.