Who was the second khalifa after abubakr?

The second Khalifa after Abu Bakr was Umar ibn al-Khattab. He served as Khalifa from 634 to 644 CE and is known for his significant contributions to the expansion of the Islamic state, as well as for implementing various administrative and legal reforms. Umar's leadership was marked by a strong emphasis on justice and governance, earning him the title "Al-Farooq," meaning "the one who distinguishes between right and wrong." He was assassinated in 644 CE.