Auxiliary languages are artificial or constructed languages created with the intent of facilitating communication between peoples who would otherwise have difficulty communicating. They are separate from lingua francas, which are natural or organic languages that become dominant for one reason or another as means of communication between speakers of other languages.
This page is meant as a guide to the possible interests of international auxiliary languages in the realm of travel. Speakers of auxiliary languages like Esperanto often have conventions, meetups, and other gatherings on a regular basis, with speakers often traveling great distances to attend. The speakers also form communities, where an overseas speaker might easily be able to make local acquaintances.
Different auxiliary languages have risen and fallen since many were created in the 19th century. At its peak in the 1880s, Volapük had about 100,000 speakers, though now it has only a few dozen fluent speakers. Interlingua is spoken actively by a thousand and some people worldwide, like Esperanto easy to learn and understand for speakers of Romance languages. Esperanto is by far the most successful international auxiliary language, boasting over two million speakers around the world, far outdoing any of its predecessors like Volapük or its attempted successors like Ido (which has only a few thousand speakers). Esperanto even has an appreciable number of native speakers due in part to couples, whose only language in common was Esperanto, raising their children bilingual or trilingual with Esperanto as one of the languages.
The limited number of speakers is the main practical factor that limits the opportunity for a traveler to use an auxiliary language: For every person who speaks any auxiliary language, there are 500 others who speak Mandarin Chinese, 250 who speak English or Hindi, 200 who speak Spanish, and 150 who speak Russian or Arabic. Instead, speakers should specifically seek out the speaker communities, or individuals, to have use of the former languages.
The speakers of auxiliary languages are not evenly distributed; the chance to find somebody who could communicate with you in that language is much higher in some regions.
There are no reliable statistics about Esperanto speakers, but it seems there are more speakers than on average in certain parts of Europe, China, Korea, Japan, Iran, Brazil, Argentina, Mexico, Togo and Madagaskar.
The first auxiliary language to gain enough ground to have large conferences was Volapük, which held meetings throughout its heyday in the 1880s, with the last one in Paris in 1889, in which participants spoke only in Volapük. Esperanto surpassed Volapük in popularity in the 1890s, and the first Esperanto Congress, the Universal Congress of Esperanto (Universala Kongreso de Esperanto), was held in Boulogne-sur-Mer in 1905. Nearly seven hundred participants, with many from France and Germany, attended. The Universal Esperanto Association has held yearly conferences ever since then, with hiatuses during the world wars. Ido, a relative of Esperanto, has been the subject of conferences since the 1920s.
Of the handful of these languages with substantial communities, a few have meetings and conventions. Esperanto has multiple events most years. Ido has at least one event every year. Interlingua also has at least one event every year.
As the speakers usually appreciate meeting fellow speakers, there may be possibilities to have a local host, if you know the language. For Esperanto this is formalized in the Pasporta Servo.
As the auxiliary languages are a try at replacing lingua francas, such as English, using those in the auxiliary language communities is a touchy issue. Trying to use your own language, the local language, and gestures, where your ability in the auxiliary language in question is not sufficient, may be better received. This of course also depends on the situation and whom you are talking to. It may also be possible to bend words of some other language into a form resembling that of the auxiliary language.