Written Chinese is a writing system that uses Chinese characters and other symbols to represent the Chinese languages. Chinese characters do not directly represent pronunciation, unlike letters in an alphabet or syllabograms in a syllabary. Rather, the writing system is morphosyllabic: characters are one spoken syllable in length, but generally correspond to morphemes in the language, which may either be independent words, or part of a polysyllabic word. Most characters are constructed from smaller components that may reflect the character's meaning or pronunciation. Literacy requires the memorization of thousands of characters; college-educated Chinese speakers know approximately 4,000. This has led in part to the adoption of complementary transliteration systems as a means of representing the pronunciation of Chinese.