The history of communication technologies (media and appropriate inscription tools) have evolved in tandem with shifts in political and economic systems, and by extension, systems of power. Communication can range from very subtle processes of exchange, to full conversations and mass communication. The history of communication itself can be traced back since the origin of speech circa 500,000 BCE. The use of technology in communication may be considered since the first use of symbols about 30,000 years BCE. Among the symbols used, there are cave paintings, petroglyphs, pictograms and ideograms. Writing was a major innovation, as well as printing technology and, more recently, telecommunications and the Internet.