People usually write letters on a type of paper called washi, which is made from rice husks or mulberry bark. The washi is very strong and holds ink well, without smudging. It also is somewhat water-resistant, so letters will not be damaged if they get damp. Letters are written with a small brush dipped in sumi (india ink)
The Japanese alphabet has thousands of characters, which were borrowed from the Chinese alphabet (most Japanese characters are almost identical to Chinese characters). It takes many years to learn all of the characters, so students have to study very hard just in order to read and write.
Education has always been highly respected in Japanese society, and one of the greatest compliments goy can give to a person is to call them sensei , or "teacher"