I would like to know if there are some areas where people use Esperanto, e.g. In religion, some use Latin, some clubs of sci-fi use Klingon. Who uses Esperanto?
Esperanto can be found in many places. Certainly people use Esperanto at Esperanto events and online, but it is also used in other places.
The Chinese government has an Esperanto news service and when I visited China I was able to get an audio tour of the Forbidden City in Esperanto.
You can use Esperanto to travel cheaply with the Pasporta Servo.
Esperanto is often used in movies and books. (For example, it shows up in Blade and Red Dwarf.)
People grow up speaking Esperanto when their parents meet at an Esperanto convention and don't speak each other's native language.
You can use Esperanto for your computer if you run Linux. Most Linux applications have Esperanto translations.
You can even attend university using Esperanto. There are schools that teach degrees in Interlinguistics using Esperanto as the language of instruction.
Most importantly though, you can use Esperanto for whatever you want to use it for. :)
Where do people use Esperanto?
I have personally used it to move furniture around town, steer a boat, cook, talk about the best way to get back home and avoid the rain during a bicycle tour...
I have used Esperanto to discuss career opportunities, plan investments, playing with kids...
I use Esperanto with my friends in chat (telegramo) where we've discussed the merits of literature and the advantages and disadvantages of the copyright system. We've discussed which countries perform best at the Olympics.
I have listened to a lecture about Freifunk, the free internet, at the local Esperanto club. I have lectured myself about other languages in Esperanto.
Where have I used it? At international events. At the local club. In interactions with people far away from me (chat, facebook) or with specific interests (goodreads). In interactions with people near and dear to me. On my sofa. At an Italian restaurant. At the beach.
There are a few religions that ask their members to learn Esperanto or groups within the religion practice Esperanto:
Oomoto, Bahá'í Faith, Spiritism. Read about these religions: http://www.101languages.net/esperanto/religion.html
Vatican Radio transmits in Esperanto.
The oldest still being published magazine, is "La Espero Katolika", also from Vatican.
The Bible, the teachings of Buddha, The Qur’an, The Book of Mormon, had been translated into Esperanto.
China Radio International has a daily program in Esperanto and a huge web site in Esperanto. http://esperanto.cri.cn/
Bona Espero in Brazil is a farm-school, where about 70 orphans learn and work. Everybody speaks Esperanto. https://eo.wikipedia.org/wiki/Bona_Espero
Zamenhof Instituto, a School in Lome, Togo, Africa. Teachers and students speak Esperanto. http://esperantofre.com/izo/index.htm
And all the events organized by Esperanto speakers or Esperanto organizations. You can find a partial listing here: http://www.eventoj.hu/2016.htm
Other uses of Esperanto: http://esperantofre.com/faktoj/
I used Esperanto about a week ago at my front door.
In spite of our posted “No Soliciting” sign, a fellow, wearing sunglasses, rang our doorbell, and started in with a spiel about surveying the neighborhood for people interested in selling their homes.
At this point, without another language to fall back on, I would have had only the two options of caving in to the intrusion, or getting angry about the intrusion. With another language to fall back on, a third option is available: pretend not to speak English, and this is what I did.
Esperanto is the only language besides English that I have serious command of, and so that is the language I use. After his spiel, I said, “Ni ne parolas angle.” After a pause during which he seemed (as I had hoped) thrown off balance, I then said, “Havu bonan vesperon!”, and gently closed the door on him. The young man presumably went away with the idea that he had simply failed to establish communication. This is vastly preferable to having an angry young man knowing where I live...
Such use of Esperanto was certainly not what I anticipated when I learned Esperanto many years ago, but, as the years rolled by, it turned out to be the most frequent use that I have made of it: brushing off bums – without angering them! – in various locales, such as downtown Dallas, downtown Miami, downtown Chicago...
Pretending not to speak your native language (a topic not unknown in literature, by the way), in a convincing way is no easy matter. If you just talk jibberish, you will not be able to keep it up consistently and boldly enough to be believed for more than a few seconds. It takes another genuine languae to fall back on, and the easiest such language is Esperanto. Note that the “rarity” of Esperanto speakers is actually an advantage in such situations. (When Esperanto is no longer “rare”, we will be living in a completely different world anyway.)