A steel instrument you play with your hands, tuned so that every note goes with every other. You do not need to read music to make it sound good.
A handpan is two shells of thin steel glued together, like a flying saucer about 50 cm across. On the top shell the maker hammers and tunes the notes, the bottom shell has a hole that works like the body of a guitar and gives the bass.
The dome in the centre is the ding, the lowest note. Around it sit 7 to 9 tone fields, from low to high in a circle. Some instruments add extra notes on the bottom shell, written as 9+1 or 12+3.
A handpan is tuned to a single scale and cannot be retuned at home. That is the trick: there are no wrong notes, so you play by feel from the first minute. It also means the scale is the main choice when you buy one.
In 2000 PANArt in Bern, Switzerland, presented the Hang, the first instrument of this kind. Other makers later built their own versions, and "handpan" became the common name for all of them.
You do not need your own instrument for the first lesson. Try the playable handpan on this site, watch the first free lesson, and if you like it, take a lesson online or in Valencia.