The twelve tribes of Israel – the twelve sons of Jacob:

Jacob had twelve sons, and these twelve sons of Jacob became the tribes of Israel.

From the status of being the twelve tribes, they also became the twelve months on the Hebrew, Jewish calendar.

Jacob’s twelve sons (in order of birth), 1: Reuben, 2: Simeon, 3: Levi, 4: Judah, 5: Dan, 6: Naphtali,

7: Gad, 8: Asher, 9: Issachar, 10: Zebulun, 11: Joseph and 12: Benjamin,

became the ancestors of twelve tribes, with the exception of Joseph, whose two sons Mannasseh and Ephraim, who were adopted by Jacob, also became tribal eponyms (Genesis 49:1-28).

The patriarchy structure of the 12 tribes:

Because the tribes were named after sons or grandsons of Jacob (patriarchy order),

whose name was changed to Israel after he wrestled an angel of the Lord, the Hebrew people became known as Israelites.

In the book of Revelation, the twelve sons of Jacob are part of the patriarchy order of the 24 elders,

The 12 sons of Jacob also representing the twelve gates which surrounds the Holy city of Jerusalem in Heaven as it is written in Revelation 21:12-13.

Sources: The images of the twelve tribes are taken from http://www.biblefunforkids.com/2012/08/the-12-sons-of-jacob-vs-12-tribes-of