Communication of ideas is central to civilization, and written records are needed. For a long time, ideas were shared through speaking and listening before writing was invented. Writing materials were difficult to find, so people used surfaces like stone, metal, wood, and bark to write on. For ages, people sought easier writing materials, and finally paper was invented in China in 105 AD. Before paper, knowledge was very restricted as books were written on heavy materials like stone or wood that were difficult to transport. In contrast, today's digital world allows vast amounts of information to be easily carried. Paper has made the publication and spread of knowledge simple. It has significantly advanced our lives.