TESOL is a form of education provided to students all over the world whose primary language isn't English. TESOL/ESL/EFL/TEFL are all acronyms generally meaning "Teaching English to Speakers Of Other Languages". . .It's taught to all ages and levels from kindergarten and all the way onward and upward through primary schools, middle schools, high schools, universities and private language schools and collages. Many non English speaking countries often have a need to employ people to teach English speech and listening skills to their students. English is almost a "must have" second language in many countries all over the world making TESOL teaching a great career choice...especially if you love to work and travel.
Well the answer to that question really lays with you. My own personal experience saw me teaching at one school only in China for 8 years. Most contracts offered seem to be for 1 year and if the school is happy with your work ethic and you in turn also like the job and location you may get asked to re-sign a new contract , this can come with great incentives, many schools will often add extra bonuses like free return flights home, a rise in wages, free sight seeing trips within their own country etc. So for many people the answer to the question about teaching ESL's potential as a long term career often becomes "Why Not? Genuinely helping people makes the job satisfying, reasonable wages (comparatively speaking) and most living costs already catered for. You can potentially travel to anywhere in the world and often get free airfares back home every year if you re-sign. It's certainly worth considering.
As far as wages go, it can depend on your location. Some countries pay much bigger salaries often akin to cost of living associated with the countries you choose. Your decision whether to teach at a private company, university, private or public school can all also influences how much money you can make and how many hours you are expected to teach each week. It can also sometimes depend on how many years experience you have and what kind of ESL certification or higher education you have obtained. It can be lucrative depending on the country you choose to teach in and you can usually find that even in the countries with lower wages and living costs, you can still save a reasonable amount whilst living quiet comfortably. Putting the money talk aside, teaching ESL can also be extremely satisfying and fun. There are many positions available all over the world for ESL teachers and most good and worthy places of employment actually cover most living expenses as well as giving you a reasonable wage. For example-
Accommodation is nearly always supplied, utilities paid for, general medical insurance taken out for you and even meal money could be on the cards, depending what kind of facility you teach at. These are good questions to ask potential employers when seeking ESL jobs.
To Find out more about how to become an ESL Teacher see this blog post