The original :
纸的发明对世界文化和国家交流是一个重大的贡献。最早的汉字是刻在动物的骨头或乌龟壳上的。战国时期（the Warring States Period ）,文字开始被刻在竹简上（bamboo slips）上。然而，骨头、竹片和木头都非常重，不便于携带。到了西汉时期，当时的贵族（noble caste）用的是丝绸或棉花做的薄纸。这种纸不仅便于书写，还特别适合作画。但是其造价太高，平民百姓根本承受不起。公元105年，东汉官员蔡伦在学习总结前任造纸方法的基础上发明了一种新型的低成本植物纤维（fiber）纸。
Reference translation :
The invention of paper is a great contribution to the world's cultural development and international communication.The earliest Chinese characters were carved on animals bones or tortoise's shells.During the warring States Period, bamboo slips were used instead.However,bones ,bamboo slips ,wood were too heavy to carry.During the Western Han dynasty, the noble caste wrote on thin paper made from silk or cotton.It's easy to write and even excellent to paint on this kind of paper.However,it was so expensive that the civilians couldn't afford it.In 105 A.D. ,Cai Lun,a high-ranking official in the Eastern Han Dynasty ,learned from the old way of paper making AMD invented a new kind of cheap plant fiber paper.
