From so many different forms of dance emerges one that can use them all or throw them all away and start over. This is contemporary dance. It is a melding of many styles but underlying it all is control and artistry. It is a genre that is recognized as a standalone performing art. There are plenty of dance companies that are based only on this form of dance. It is more about a philosophy than a standardized technique or choreography. It embraces improvisation and philosophies from most forms of dance. Professionals often have formal training in ballet, modern dance, and postmodern dance.
In a broader sense, contemporary is sometimes used to describe all dance that is not classical jazz or traditional folk dance. It is a catch all phrase for dance that doesn't really fit anywhere else. But that is a bit of a naive understanding of this form. It is more an experiment and thought exercise in dance than an actual standardized form of dance. It is conceptual, thematic, and filled with emotion. It is an expression in a more powerful way than most types of dance. It focuses on its message more than on its steps.
Steps in contemporary are pulled from everywhere: ballet, jazz, ballroom, folk; as well as from the imagination, fusion, and melding of all dance forms into one. It is sometimes even called non-dance and conceptual dance. It has permeated all standardized forms of dance. You can't study or perform any form of dance without getting exposed to this non-dance. All dance forms incorporate it and it incorporates them. It is a symbiosis that creates new and beautiful movement. It first began to be explored in the 1960's. The leaders in this form of dance experimented and came up with wildly successful pieces that are still performed today.
These geniuses of dance such as Martha Graham, Paul Taylor, Francois Delsarte, Emile Jaques-Delcroze, Marie Rambert, and many others took a solid foundation of technique and twisted it into a new amazing form that embraced the time and season. But concept of embracing also made it timeless, adaptable to every time and season. It is a welcome canvas to artists ahead of their time as well as ones who want to visit the past. It is built upon a firm foundation of classic forms of dance, but has also evolved its own technique such as Alexander technique, Graham technique, and many others.