Online instruction has helped millions around the world gain competency and credits toward certification and academic degrees. Massive Open Online Courses (MOOCs) are courses that are, generally speaking, open to all, offered at the learner’s own pace and free of charge for those not seeking certification. First launched in 2008, the MOOC phenomenon has firmly taken root, and in the meantime, ever more opportunities to obtain knowledge and education have appeared on the horizon. Here’s just a quick survey of today’s online educational landscape:

Coursera is one of the largest providers of online courses. Founded in 2012 by a pair of professors from Stanford University, more than 70 million learners have benefited from its offerings including online courses, degrees, specializations, guided projects and professional courses. These are offered by more than 200 international universities and companies, including Yale, Duke University, McMaster University, IBM, Google and a host of others. Reviews and ratings provided by former class participants help would-be participants understand if the course would suit their own particular needs. In addition to the free/no-credit course offerings, one could expect to pay from $39 per month for a four to six-month specialization offering mastery in a specific career skill, or from $9,000 for an online bachelor’s or master’s degree.

EdX is another big name in online education. Similar in approach to Coursera, EdX offers a wealth of courses in the humanities, natural sciences and other, more obscure disciplines. Here too will you find many courses free of charge. EdX-verified courses offer learners certificates of completion, whereas credit-eligible courses offer credits to those working toward a degree. College-bound high school students can benefit from over 30 AP (Advanced Placement) courses in subjects from calculus to psychology, with the option to take AP exams and qualify for college credits.

Some of the EdX course offerings sound downright fun, such as a 12-module course titled “Beer: the science of brewing,” in which learners can discover how brewing processes influence the taste and aroma of beer.

Udacity offers targeted training to those seeking careers in high-tech fields. Courses are not taught by professors or academics but rather industry leaders in positions to know which skills are most in-demand now and into the future. Learners from the U.S. and across the globe can choose from subjects including programming and development, artificial intelligence, cloud computing, data science, business and autonomous systems. Udacity helps its learners to land jobs upon completion of their studies by assisting them in the creation of project portfolios and prepping them for job interviews.

In partnership with the professional services company Accenture, Udacity offers a Veteran Technology Training Program designed to equip veterans with the skills needed to become an entry-level Software Engineering Associate. Once selected, veterans can enroll, free of charge, into an Intro to Java course.

Udacity differs from other MOOCs in the fact it offers users something called Nanodegrees. Motivated learners can generally secure one of these non-accredited degrees within several months of intensive study. Costs vary, and discounts are often available.

University of the People, or UoPeople, bills itself as the world’s first non-profit, tuition-free, accredited and wholly online American university. Founded in 2009 by the entrepreneur Shai Reshef, UoPeople was conceived to provide access to university studies to qualified high school graduates from around the world, despite the financial, geographic, societal or personal constraints they might face. Envisioned as a game-changer for underserved students from around the world, today UoPeople has more than 14,000 students from more than 200 countries and territories enrolled. UoPeople offers associate and bachelor degree programs in business administration, computer science and health science, as well as master’s degree programs in business administration and education.

Whether for fun or future prospects, online instruction is an ever more viable option, and an overseas posting can no longer be considered a detriment to further education.