The Nile (Arabic: النيل an-nīl), in Africa, is one of the two longest rivers on Earth. Whether the Nile is longer than South America's Amazon still remains the subject of much debate. This is, for the most part, due to two reasons: first, the lengths of rivers vary over time (especially in plains, where rivers often change course), and, second, the point from which the length of a river is measured is not always agreed upon. The Nile lost several miles of meanders in Nubia when Lake Nasser was formed.

Lake Victoria in Uganda is commonly considered to be the source of the Nile, although the lake itself has feeder rivers of considerable size from the other Great Lakes. In particular, the farthest headstream of the Nile is the Ruvyironza River in Burundi, which is an upper branch of the Kagera River. The Kagera flows for 690 km (429 miles) before reaching Lake Victoria.

Leaving Lake Victoria, the river is known as the Victoria Nile. It flows further for approximately 500 km (300 miles), through Lake Kyoga, until it reaches Lake Albert. After leaving Lake Albert, the river is known as the Albert Nile. It then flows into Sudan, where it becomes known as the Bahr al Jabal. At the confluence of the Bahr al Jabal with the Bahr el Ghazal, itself 720 km (445 miles) long, the river beomes known as the Bahr al Abyad, or the White Nile, from the clay suspended in its waters. From there, the river flows to Khartoum.

Meanwhile, the Blue Nile (or Bahr al Azraq) springs from Lake Tana in the Ethiopian Highlands. The Blue Nile flows about 1,400 km (850 miles) to Khartoum, where the Blue Nile and White Nile join to form "the Nile."

After the Blue and White Niles merge, the only remaining major tributary is the Atbara River, which originates in Ethiopia north of Lake Tana, and is approximately 800 km (500 miles) long. It joins the Nile approximately 300 km (200 miles) past Khartoum.