So, many used books simply end up neglected and forgotten on bookshelves, in boxes or even in rubbish bins.
It's a terrible waste. Such books could mean a lot to children who don't have any, according to teen advocates of Kids4Kids, a local charity.
The teens have launched their Books for a Cause campaign, which will end in a seven-day collection drive. Between May 30 and June 6 students all around Hong Kong can donate used books at their school.
The collected books will be given to the Crossroads Foundation and the Chi Heng Foundation, which will pass them on to underprivileged children in and outside Hong Kong. No books will be wasted. Those that are too worn will be sent for recycling.
Kids4Kids was founded by Michele Lai Pek-lian in 2008. It encourages youngsters to reach out to less-fortunate children and give them a hand. "At first, the organisation was run by adults, but then I thought 'Why should we adults tell children what to do? Let them tell us what they want to do'," Lai says.
Now all the charity's events, including Books for a Cause, are launched and run by teenagers aged 13 to 17. They study in different schools around Hong Kong.
What they have in common is their passion for their cause.
"Many children don't have access to books," says 17-year-old Denise Chan Wing-sze, president of Kids4Kids and a student at Chinese International School.
"Just by giving one book, we can all do something for them."
The charity's vice-president, Kelvin Ha Cheung-hin, agrees.
"Books are doors to different worlds. We can learn so much about the world through them," he says.
Kelvin, also 17, a student at Canadian International School, is in charge of marketing and has produced a cool promotional video for the book collection drive.
Members of the team have been visiting schools to encourage students to take part. They've also made presentations to businesses, including the management team of investment firm Morgan Stanley's Hong Kong branch, to seek their support.
"I used to think that businesspeople only cared about money," says 16-year-old Denise Wong Kwun-yin of Chinese International School, who is the campaign's project manager. "But they are actually dedicated to volunteer work and are willing to give."
The student team's hope is to collect one million books during the seven days. They say that would make their effort a world record. But it's not about breaking records, they stress.
"It's the passion that counts, that we work hard to engage students in taking action to help others," Kelvin says.
Kwun-yin adds: "The message we want to give to young people is this: you have the power to make the world a better place."
Wing-sze echoed a common sentiment among youngsters. "There are times when I think 'I'm just a kid. What can I do'?" she says. But that is the wrong approach. "Through the work we are doing, I realise we can make a difference in other children's lives and in our world," she says.
Kids4Kids is looking for local students to help out with their Books for a Cause initiative. You can become a co-ordinator for the collection of used books in your school. For more details and registration form, visit www.Kids4Kids.org.hk
Young Post is recruiting Junior Reporters to take part in the event and share their experiences about it. Send an e-mail with "books for all" in the subject line to firstname.lastname@example.org. Please don't forget to give your name, age, school and contact details.