How did most of the world learn to read in just 200 years?

Most of the world learned to read in just two centuries because cheap books and mass schooling finally put reading within everyone's reach. Literacy, traditionally the ability to read and write, was a rare privilege for most of history: probably under 1% of people in ancient Egypt, perhaps 5 to 10% in classical Greece. In 1820, only about 12% of the world's people could read. By 2022, it was about 87%.

The printing press of the 1400s helped, but it wasn't enough. Paper and books only became affordable to all classes with the Industrial Revolution in the mid-1800s. Religion and politics pushed too. Sweden's 1686 church law made literacy compulsory so that every Lutheran could read the scriptures, and by 1800 almost everyone in Sweden could read, although many, especially women, still couldn't write.

The fight for literacy has been political. In 1940s Brazil, you had to be literate to vote. In 1962, the educator Paulo Freire's method taught 300 sugarcane harvesters to read and write in 45 days. Two years later, after a military coup, he was jailed for 70 days.

The story isn't over. Because the population grew so fast, the number of adults who can't read was still higher in 2015 than in 1950. Two-thirds of them are women. And school isn't the same as reading: in Malawi, up to 90% of second-graders couldn't read a single word.