世界上最长的河流是尼罗河，流经非洲东北部，总长度约为6650公里。尼罗河源于布隆迪高原，经过坦桑尼亚、卢旺达、布隆迪、刚果民主共和国、南苏丹、苏丹和埃及七个国家，最终注入地中海。

尼罗河是非洲最重要的河流之一，对周边国家的经济和农业发展都有着重要的影响。它为周边地区提供了充足的水源，支持了大量的灌溉农业和养殖业。此外，河流还是很多城市和村庄的主要水源。

在尼罗河上还有许多著名的景点和历史遗迹，如埃及的金字塔和卢克索神庙等。这些景点吸引了众多游客前来参观游览。

总之，尼罗河是非常重要和有价值的自然资源，它的存在对世界有着重要的意义。

The world's longest river is the Nile River, which flows through northeastern Africa and has a total length of about 6,650 kilometers. The Nile River originates from the Burundi plateau, passes through Tanzania, Rwanda, Burundi, the Democratic Republic of Congo, South Sudan, Sudan, and Egypt, and ultimately flows into the Mediterranean Sea.

The Nile River is one of the most important rivers in Africa, and it has a significant impact on the economies and agricultural development of surrounding countries. It provides abundant water resources for irrigation agriculture and animal husbandry. In addition, the river is also the main source of water for many cities and villages.

There are many famous tourist attractions and historical sites on the Nile River, such as the pyramids and Luxor Temple in Egypt. These attractions attract many tourists to visit.

In summary, the Nile River is a very important and valuable natural resource, and its existence has important significance for the world.