A didgeridoo is made from a piece of eucalyptus tree that has been hollowed out by termites. Yes, really - tiny insects do most of the work, eating away the soft inside while leaving the hard outer wood. The maker then cleans it, paints it with traditional designs, and adds a little wax for the mouthpiece.
To play it, you press your lips against one end and blow a long, buzzing sound. The really clever bit is a trick called 'circular breathing'. Skilled players keep the note going for minutes at a time by breathing in through their nose and out through their mouth at the same time. It takes years to learn.
The sound of a didgeridoo is deep and warm - somewhere between a low hum and the rumble of an engine. Good players can copy the calls of birds and animals in the middle of their playing, so a song might suddenly sound like a kookaburra laughing or a kangaroo thumping.
Didgeridoos are an important part of Aboriginal culture, especially in northern Australia. They are often played at ceremonies, celebrations and community gatherings. Today many Australian musicians, both Indigenous and not, use them in modern music too.