A very brief history lesson
Apparently, wood was the substrate used by most artists until the 16th century. It was a very prestigious medium in Greece and Rome. The oldest surviving Greek paintings are a series of 6th century BC painted tablets from Pitsa.
The old masters painted on many different types of wood, depending on what was locally available. For example, Albrecht Dürer (1471–1528) painted on poplar when he was in Venice and on oak when in the Netherlands and southern Germany. Leonardo da Vinci (1452–1519) used oak for his paintings in France. Hans Holbein (1497/8–1543) used oak while working in southern Germany and England.
The move towards canvas
In the 16th century, canvas began to gain popularity in Venice. Italians were making the best quality canvas at that point, for sails. Mantegna led the change from wood to the cheaper and more portable option of canvas.
Canvas has been the substrate of choice for all serious works of art since then. However, wooden panels have seen something of a renaissance recently and are being recognised as one of the most durable and archival supports available to painters today.
The advantages of painting on wood
I love wood because of its smooth surface. It feels more like working on paper than canvas does. The smoothness and firmness means that it is easier to use many different media on wood compared to canvas. For me, this increases the level of detail I might be able to achieve. I also appreciate the greater freedom this accords me when correcting for those little 'accidents' happy or otherwise.
You can even use watercolour on wood. If you are interested in this, you might want to check out this tutorial.
Sourcing wood for painting
I do understand that since it is only wood, it is possible to paint on any piece of wood. That is just a little bit too much effort prior to getting into the fun of painting for my liking. If you are more patient and skilled at carpentry than I, you can find your own wood, or even hardwood and gesso it to create a lovely solid, smooth painting surface. Lori McNee demonstrates in this video, if you are interested.
But my preference is for ready-to-go cradled wood panels. I kept seeing artists using them in my online travels and they appear to be easily available in America and Europe. However, I live in Australia, and they have been hard to find out here. I have finally found some (obviously...) Cavalier Art ship Australia wide, as far as I understand, so if you are a fellow Aussie that might help you out.
I rather like that what was old is now new again. I am happily embracing wood panels and looking forward to experimenting a bit more with them. Hopefully, you will too!