World Book Day is observed in more than 100 countries as a celebration of the joys of reading.

But reading is not just about pleasure: books have the power to touch us profoundly, to open our eyes to injustices – and sometimes even act as a catalyst for social change.

To mark World Book Day, we take a look at some of the novels that have changed society.

Uncle Tom’s Cabin, Harriet Beecher Stowe

“So you’re the little woman who wrote the book that started this great war.” This was how Abraham Lincoln reportedly greeted Harriet Beecher Stowe when he met her in 1862, a decade after she wrote Uncle Tom’s Cabin, the second-best selling book of the 19th century after the Bible.

The story of Uncle Tom, an African-American slave, brought the horrors of slavery to the attention of the public on a personal level for the first time, causing an uproar.

The novel greatly furthered the abolitionist cause in the north, ratcheted up tensions with southern slaveholders and, as Lincoln suggested, possibly even helped tip the country into civil war.

The Jungle by Upton Sinclair

Muckraking journalist Upton Sinclair’s 1906 novel portrays the harsh working conditions, extreme poverty and exploitation faced by the mainly immigrant labourers in Chicago’s meat-packing industry.

Although the book was written to highlight the plight of the working poor and the deep-rooted corruption of people in power, it also sparked a public outcry over food hygiene. Sinclair famously complained:“I aimed for the public’s heart and by accident I hit it in the stomach.”

Still, it is arguably considered one of the most politically influential American novels of the last century.

After reading The Jungle, President Theodore Roosevelt commissioned an investigation into Chicago’s meat-packing industry. Within a year, the Meat Inspection Act was passed, along with the Pure Food and Drug Act, which later paved the way for the Food and Drug Administration.

All Quiet on the Western Front by Erich Maria Remarque

One of the best-known anti-war novels, All Quiet on the Western Front depicts the horrors of the First World War trenches from the perspective of a young German soldier.

Translated into more than 20 languages and adapted into a celebrated Hollywood film in 1930, the book spoke for a generation that had been, in Remarque’s words, “destroyed by war, even though it might have escaped its shells”.

It deals with the futility of conflict and attracted both praise and harsh criticism at the time, mostly from Remarque’s fellow countrymen, who felt it denigrated the German war effort. It was among the books banned and publicly burned by the Nazis.

Things Fall Apart by Chinua Achebe

Perhaps the best-known novel of Nigerian novelist, poet and essayist Chinua Achebe describes a tribal society falling apart as a result of the arrival of Christian missionaries.

Written in 1958, the novel has sold more than 10 million copies around the world and has been published in some 50 languages. It is still widely read and studied as an example of the impact of colonialism on African culture and identity.

The Ragged Trousered Philanthropists by Robert Tressell

Robert Tressell’s 1914 socialist polemic about a group of honest men exploited by money-grabbing capitalists was based on the injustices faced by the working classes in Edwardian England.

The workers are “philanthropists” because they slave away for a pittance, essentially giving away the value of their labour to their employers.

The novel was an integral part of the drive for social reform at the start of the last century.

The Grapes of Wrath by John Steinbeck

The 1939 classic chronicles a penniless Oklahoma family’s journey westward along Route 66.

An immediate bestseller, the novel highlighted the shocking Depression-era poverty and destitution of hundreds of thousands of migrants making the journey to California to find work.

The book was banned and burned in a number of places, including Kern County, California, where the Joad family’s journey ended.

1984 by George Orwell

George Orwell’s dystopian work about life under a totalitarian regime inspired a whole subgenre of books, such as Anthony Burgess’s A Clockwork Orange, that envision the future as a nightmarish place with no freedoms or rights.

Terms from 1984, including “Big Brother”, “doublethink” and “thoughtcrime” are still commonly used today. The novel is a poignant reminder of the importance of freedom of thought and speech.

To Kill a Mocking Bird by Harper Lee

“You never really understand a person until you consider things from his point of view … until you climb into his skin and walk around in it.”

The words of Atticus Finch in Harper Lee’s 1960 tale of racial inequality in 1930s Alabama still resonate with readers around the world today. The book has left an indelible mark on generations and is a valuable lesson in looking at the world through another person’s eyes.

Beloved by Toni Morrison

Nobel laureate Toni Morrison reportedly spent three years thinking about her Pulitzer-winning novel before writing a word.

Beloved, which deals with the legacy of slavery, was voted the best work of American fiction in the past 25 years by the New York Times.

It was inspired by the story of a runaway slave who, rather than give up her children to her former "owners" when they came looking for her, cut her daughter’s throat.