The political leaders of each side will participate in the last televised debate before the Sept. 18 referendum on Monday night. Here's what you need to know.

When did Scotland and England unite?

The Act of Union between Scotland and England was signed on Jan. 16, 1707. It came into effect on May 1 of that year, creating the United Kingdom of Britain. The Scottish Parliament was dissolved, and a single Parliament was created at Westminster in London.

Why did Scotland and England join in the first place?

Scotland and England have a complicated history, but the short answer is that Scotland needed an economic boost. The country's finances were a mess after a failed attempt to establish a trading colony in Panama. This unsuccessful scheme "was conclusive evidence that Scotland's future prosperity was best served by union," The Guardian writes.