I didn't know what it was either till I joined 365. Even when I have created it by pure fluke. Well done for ticking off another one from the bucket list.
@chessington The camera creates this effect on points of light in the darkness when they are out of focus. Candle flames, fairy lights and glints of sunlight on dark water all create bokeh in backgrounds out of focus. I changed my camera to manual focus to shoot our outdoor fairy light out of focus. Have fun!