Art nouveau glass is a kind of glass that is very fancy and pretty. It was popular a long time ago, when grown-ups were kids, and it still is today. Art nouveau glass is made in a special way using really hot ovens called furnaces.
When the glass is hot, it can be shaped into all kinds of cool shapes and colors like flowers, leaves, and swirls. These shapes make art nouveau glass look like it came from a magical world.
People use art nouveau glass to make all sorts of things, like cups, vases, and lamps. Some very special glass artists can even make art nouveau glass windows that look like rainbows shining through a room.
So, art nouveau glass is just like making fancy and beautiful pictures with really hot glass. And it's a lot of fun!