Reaching the parts others cannot teach
It's easy to take online learning for granted, whether it's finding how to do something on YouTube or following a free online course from a university.
But Cheril Demasuhid doesn't take it for granted. It's immensely important to her.
She is working as a maid in Hong Kong so that she can send back money to her family in the Philippines. In her spare hours, she goes on to the internet to study subjects such as IT and business.
Sometimes she studies alone, sometimes together in informal classes with other migrant workers.
When educationalists write about Moocs - massive open online courses - it is often about the technical achievement of being able to deliver chunks of higher education courses to millions of online learners.
Or else it's about the economics of universities taking their wares to a wider audience or delivering extra content for their existing students.
But Moocs - a few years after the initial hype about these digital courses - are now teaching people who would otherwise be unable to access lessons.
"I can make use of my spare time. I don't want to be a maid forever; I have a dream of building my own business online," says Ms Demasuhid.
Her employers are an Indian family and she is able to use their internet, or else she goes to the public library where she follows courses from the Alison online course provider, which has signed up more than five million students worldwide.
It's a model of global education. A Filipino in Hong Kong, working for Indians, studying courses provided by an education company in the west of Ireland.
She says she studies for "self improvement or for upcoming opportunity" and it is made possible because it is free and online.
"I am here to earn a living and to be able to help my parents and siblings in my country. I am here because I have a goal in life to alleviate my family from poverty," she says.
The question of whether online courses are really reaching under-served groups has been examined by Duke University in North Carolina in the United States.
Researchers at Duke say that too much of the interest in Moocs has focused on courses taken by "highly-educated, white for the most part, upper-middle-class folks".
But an analysis of its own online courses showed they were also being used by marginalised groups of learners.
As well as teaching migrant workers, Alison this month launched an online course for skills to get back into work, aimed at a huge group who are unable to step into a conventional classroom.
These are the more than 2.5 million people in prison in the US and many millions more who are former prisoners.
"There is a huge opportunity to address recidivism through free online education, so much so that we foresee a day when the obligation to complete free courses could represent an alternative to traditional sentencing," said Alison's chief executive Mike Feerick.
"Doing 200 hours community service may never change someone's mind or outlook on life, but completing a course of study does have that potential," says Steve Steurer, director of the US Correctional Education Association, which is a partner in the project.
Refugees are another group often missing out on education.
A course from the Commonwealth Education Trust, on the Coursera online learning platform, is being used in the Dadaab refugee camp, near the border of Kenya and Somalia. It is aimed at providing teacher training lessons for students without any formal teacher education.
The course is being delivered through a mini "learning hub" set up at the refugee camp. And in terms of the scale of the need, this "camp" has a population of 350,000 people.
The Duke University researchers identified retired people as a particular niche group of online course users, who might want to keep their minds active, but who also had limits on mobility and money.
Stewart West, an 81-year-old former soldier and policeman living in Malaysia, has been using the Futurelearn online learning network to follow courses about ageing.
"Instead of being housebound I now feel completely engaged with the outside world and can fill in gaps in my knowledge or enter new areas of study as and when I wish," he said.
But the idea of online courses providing a way out isn't only about geography or poverty. It's also about people wanting a second chance.
Franciso Goitia from Buenos Aires in Argentina says he took online courses from the edX online network as part of a decision to change his life and to escape a job he hated.
"I quit my job and told myself I was going to devote a year to do as many Moocs as I could and learn as much as possible."
He says that he has found a job much more to his liking now.
And Cheril Demasuhid, studying in her spare time as a maid in Hong Kong says: "Knowledge - no one can take it away from me."