The language was initiated by Ludwig Lazar Zamenhof, who created the grammar on the basis of European languages with a minimal quantity of exceptions. The vocabulary is mostly based on Romance languages, although there are also words from Germanic and other languages. The new language, the first textbook of which appeared in 1887, attracted a community of speakers and began a normal process of language evolution within a community who used it in many environments and created a culture associated with the language. Two decades later, the first children speaking in Esperanto with their parents were born, the first native speakers of the language. Thus, one can say that it is a language created for international communication, which later became creolized and is nowadays the language of a diaspora of Esperanto speakers.

It was created on the basis of the vocabulary of Indo-European languages, but was intended to be easy to learn. For this reason, its grammar is agglutinative, a characteristic feature of Turkic and Finno-Ugric languages, and at a deeper level it is isolating, as in Mandarin Chinese and Vietnamese. This means that its morphemes can be used as independent words. It has a completely regular grammar and allows the creation of a large quantity of words by combining lexical roots and about forty affixes (for example from the radical san- (healthy), it is possible to create words such as: malsana (“sick”), malsanulo (“sick person”), gemalsanuloj (“sick people of both sexes”), malsanulejo (“hospital”), sanigilo (“medicine”), saniĝinto (“person who has recovered”), sanigejo (“curing place”), malsaneto (“little illness”), malsanego (“extreme illness”), malsanegulo (“very sick person”), sanstato (“health state”), sansento (“health feeling”), sanlimo (“health limit”), malsankaŭzanto (“pathogen”), kontraŭmalsanterapio (“therapy against sickness”)…). The main parts of speech (nouns, verbs, adjectives and adverbs) have consistent endings that always allow the recognition of all parts of speech. Its regularity makes it particularly easy to learn, and its streamlined capacity to create new words make it one of the most productive languages, with a potentially unlimited number of words, it is capable of expressing all new ideas or states. For example, it is possible to write a novel about fictional table-shaped Martians and to call them tablo (“table”), tablino (“female table”), tablido (“table offspring”)… We can imagine a man who walks backwards ( inversmarŝanto , “reverse-walker”), a remedy against dogmatism ( maldogmigilo , “undogmatizer”), etc.