Not all languages use words. In some parts of the world, people communicate by putting whistling. Silbo Gomero is an example of a whistling language. It is an ancient form of communication used in La Gomera, one of Spain’s Canary Islands. Long ago, when dwellings were spread far apart in these valleys, whistling was developed as a form of communication. Relaying a message through whistling was easier than walking to a friend or relative’s home. Neighbours often whistled to warn each other of dangers. While the language seemed to be dying out in the 1950s and 60s, Silbo Gomero experienced a revival in the 90s when it became a compulsory subject at schools in La Gomera. The simple language, which is based on Spanish, has two whistles for vowels and four whistles for consonants. The length and tone of the whistles help convey the meaning. In 2009 UNESCO declared this unique language as a Masterpiece of the Oral and Intangible Heritage of Humanity.