Esperanto was initiated by L. Zamenhof at the end of the 19th century through a book called Lingvo Internacia. People who wanted to have international contacts started to learn and use the language. This is how Esperanto came into being. After a while it became stable and evolved into the language which is used and enjoyed by people in many countries.
Zamenhof presented the language in 1887 and during the first one hundred years it has been spreading around the world. The basic principles of grammar, word creation and speaking have not changed, except for the meanings of some words. Also, many new words have entered the language. One hundred years is not a long time for a language! But many people have already learned and used the language and have therefore contributed to its natural evolution.