Esperanto is a language designed to facilitate communication between people of different lands and cultures. It was first published in 1887 by Dr. L. L. Zamenhof (1859-1917) under the pseudonym "Dr. Esperanto", meaning "one who hopes", and this is the name that stuck as the name of the language itself.
Esperanto is considerably easier to learn than national languages, since its design is far simpler and more regular. Also, unlike national languages, Esperanto allows communication on an equal footing between people, with neither having the usual cultural advantage favouring a native speaker.
Esperanto's purpose is not to replace any other language, but to supplement them: Esperanto would be used as a neutral language when speaking with someone who doesn't know one's own language. The use of Esperanto would also protect minority languages, which would have a better chance of survival than in a world dominated by a few powerful languages.