There are perhaps as many artificial languages (auxlangs) in the world as natural languages. Unfortunately, only a few of these languages have more than a dozen speakers. With perhaps more speakers than all the other auxlangs combined, Esperanto has been the queen of the field for the past 100 years.
Other than Esperanto there are many exciting auxlangs and conlangs. For instance, one of them (Toki Pona) doesn't have more than 123 words to talk about everything in the world, while the vocabulary of another (Sambahsa) is inspired from proto-Indo-European (a language believed to be the mother of all Indo-European languages) and still there is a third (Lojban) that claims to have the most logical grammar.
Exciting as these languages are, I wonder if an ordinary guy on the street has much use of them. To my knowledge there exist only three languages, that you can put to some practical use after learning and these are:
It's my personal favourite. If you are reading this, you will find Interlingua the most familiar. It has its vocabulary extracted from the five major world languages namely English, French, Italian, Portuguese and Spanish. Add to that occasional sprinkling of words from German and Russian and you get a language that, with the exception of the Middle East and the Far East, can be used everywhere.
It is common to hear that there are exceptions and irregularities in Interlingua. Fortunately, you won't even notice them if you speak any of the source languages. How many of you would raise eyebrows on reading that Interlingua es is 'is' and son is 'are'? This is perfectly natural, isn't it?
There are two major advantages of learning Interlingua:
- You get an insight into how Romance languages work and after spending a few months you begin to get the gist of texts in source languages (except English).
- Your English vocabulary takes a boost.
They call it the Slavic counterpart of Interlingua. The methodology of extracting vocabulary is more of less the same but there are more source languages - Russian, Ukrainian, Belarusian, Polish, Czech, Slovak, Serbian, Bosnian, Croatian, Slovene, Bularian and Macedonian - and all of them are Slavic. A grammar of the language is available on this website but I haven't found any lessons yet. Therefore, I don't know how much it will help you in the understanding of Slavic languages. However, when I showed a few Slovianski sentences to a Russian friend, he understood almost everything.
Just like Interlingua, there are irregularities and exceptions. The difference is: we will feel the pinch this time!
And it should give you a taste of writing and reading in Slavic languages within a few months of study.
Esperanto doesn't help you understand any language. It looks ugly. The Chinese, Japanese and Koreans don't find it easy. Most speakers of the language prefer to talk about Esperanto than any other topic and they look down on other artificial languages, often calling it a "waste" of time and energy. Still, it among the three and the reason it the strength of its speakers. They are spread all over the globe and by even the most conservative estimates, there are at least 10,000 of them.
There are lots of books in Esperanto and if your dream is to see the world but you are tight on cash, Pasporta Servo (Passport Service) can help you. Through Esperanto, I have talked to people from China, Lithuania, Romania and the Democratic Republic of Congo and have learned how similar we are. But again, even here discussion about Esperanto takes at least 10% of the time.
Therefore if you are looking for a way so that you can start talking to people from all over the world without using Google Translate, Esperanto is the way to go.
I wanted to add Frenkisch too but I don't think it's ready yet and I don't know a non-English Germanic language speaker who can tell me how effective the language is.