Everything vibrates and makes sound, from the smallest living cells in the human body to the biggest skyscrapers. Sound itself is a travelling wave of vibrating particles but, amazingly, our brains can understand sounds – gathering information and meaning from these vibrations. Sounds are the building blocks for language, and culture, and can be a source of both pleasure and pain. In the modern world sound is also fantastic tool for medicine, industry and monitoring the natural environment. But it can also be polluting and bad for our health. For many animals, sound is essential for survival, enabling them to communicate, hunt and navigate their world. Hearing loss affects around 5% of the world’s population, and encouraged by the WHO, scientists across the world are working to find new ways to improve deaf people’s lives. The science of sound cuts across many disciplines - from medicine and neuroscience to the environment - and people who study sound use complex mathematics and cutting-edge technology to help us understand how sound affects us and our planet. 2020/21 was the first International Year of Sound, initiated by the International Commission for Acoustics, in response to UNESCO resolution 39C/49, as a celebration of sound and how it enters our lives in so many ways. To celebrate the year of sound, here you will find a collection of articles written by experts from the UK Acoustics Network and the International Year of Sound team. These articles explore the fascinating world of sound and how it benefits and causes problems to people, other animals, and our environment. Editorial consultant: Caryl Hart, Children’s Author.