Turkey has been an official candidate for membership in the European Union since 1999 but has made little progress in negotiations.

The European Union has been reluctant to allow Turkey to join, due in part to the country's large population and relatively poor economy. Turkey's human rights record and its treatment of minority groups are also major concerns. Turkey has made some progress in recent years in meeting the requirements for membership, but the European Union has been unwilling to grant it full membership.

The European Union has been accused of Islamophobia and racism in its treatment of Turkey, which has hindered the country's progress in negotiations.

Turkey is a vital strategic ally of the European Union, and its membership would bring considerable economic and political benefits. However, the European Union has so far been unwilling to grant Turkey full membership. 

There are a number of reasons why Turkey has found it difficult to join the European Union.

• The first reason is that Turkey is a large and populous country. It would be the largest member state of the European Union, with a population of over 80 million people. This would give Turkey a significant amount of power within the Union.
• Another reason is that Turkey is not a democracy. The country is ruled by an autocratic president, Recep Tayyip Erdogan. Erdogan has been accused of human rights abuses and of eroding the rule of law in Turkey. This has made it difficult for the European Union to accept Turkey as a member state.
• The European Union has expressed concern that allowing Turkey into the EU would result in an influx of Muslim immigrants. Turkey has also been accused of supporting militants affiliated with the Islamic State (ISIS).
• Finally, Turkey has a very different culture from the rest of Europe. It is a Muslim-majority country, and its official language is Turkish. This has made it difficult for Turkey to assimilate into European culture.

Despite these difficulties, Turkey has made some progress in negotiations with the European Union. In 2016, the European Union and Turkey reached an agreement on a refugee deal. Under the deal, Turkey agreed to take back refugees who had entered Europe through its territory. In return, the European Union agreed to provide Turkey with financial assistance.

The refugee deal has helped to ease tensions between Turkey and the European Union. However, it has not resolved all of the differences between the two sides. Turkey is still seeking full membership in the European Union, and the European Union is still reluctant to accept Turkey as a member state.