There are many forms of glass art. Kiln formed glass is one of them.
The basic idea behind kiln formed glass is that art objects can be created by melting glass in a kiln. Glass is heat-processed in a kiln at temperatures ranging from 1200 degrees to over 1900 degrees. Two or more pieces of glass are placed in the kiln and heated until they fuse together into a single piece. Glass is placed over a mold and heated until it slumps into (or drapes over) the shape. Frequently the glass being slumped has design elements already fused to it. Hours of cold-working go into each piece between each firing.