About the Book of Joel
Joel may have lived in the country called Judah. He was a prophet. And he told Israel's people, and their enemies, that God would punish them. They thought that on the ‘Day of the LORD’ he would bless them. But on that day he would punish them. But after God had punished his people, he would again show his love to them. He would send them his Holy Spirit.
The Day of the LORD was an idea that several prophets had given to Israel. Most people thought that the LORD would then make Israel rule all the other countries in the world.