International Literacy Day on 8 September celebrated the importance of literacy to individuals, communities and countries. Literacy rates have improved over the past 20 years but significant inequalities remain, with women and girls more likely to miss out on basic education.
The latest global data from this month shows that 773.5 million adults - 64 per cent of whom are women - still lack basic reading and writing skills.
Irina Bokova, director-general of the United Nations Educational, Scientific and Cultural Organisation (Unesco), which organises International Literacy Day, said: "Literacy is the key for acquiring knowledge, interpersonal skills, expertise and the ability to live together in community - all skills that are the foundations of modern society.
"In the 21st century, more than ever before, literacy is the cornerstone of peace and development."
Literacy is defined as the ability to read and write short, simple statements, such as "the child is reading a book".
Unesco has pointed out that regional averages can mask disparities between countries and that people can overestimate their literacy skills. Traditionally, the concept of literacy has centred around books and reading and writing, but Unesco noted that new forms of literacy were emerging as technology advanced.
In Sub-saharan Africa
25% - Adult literacy rate in Guinea
94% - Adult literacy rate in Equatorial Guinea
Global literacy rates
Adult women (aged 15 and over) 79.9%
Young women (aged 15-24) 86.8%
Adult men 88.6%
Young men 92.2%.