Thomas Jefferson was the third President of the United States, serving from 1801 to 1809. He was also a founding father and author of the Declaration of Independence. Jefferson was a proponent of individual liberty and limited government, and his political philosophy helped shape the early American republic. During his presidency, he oversaw the Louisiana Purchase, which doubled the size of the United States, and also established a policy of economic embargo against Britain and France. However, his presidency was also marred by controversies such as the Burr conspiracy and his handling of the Barbary Wars. Jefferson's legacy continues to be debated and analyzed to this day.