Only a few years ago, less than a few hundred people could read Chu Nom, the older writing system of the Vietnamese language.  Now, thanks to the Internet and efforts of Chu Nom enthusiasts, people can learn this script that connects Vietnam with its Chinese lexical heritage, and allow learners to gain a deeper appreciation of etymology and its connection to the greater East Asian cultures.

This is from the Tien Quan Ca 进军歌 — the national anthem of Cong Hoa Xa Hoi Chu Nghia Viet Nam 共和社会主义越南.  The three underlined letters are Chu Nom, while the other characters are common with Chinese, Korean and Japanese (with some variations).  Like in English (that borrows a lot from Germanic and Latin languages) many simpler and common words are of the older, native origin before the heavy lexical borrowings began. Hence in this case, mau, ra and sa are indigenous Kinh Vietnamese words meaning quickly, go out, and drop, respectively. In order to write these words out, they have used Chinese letters with sounds (in Vietnamese pronunciation) mau 毛, ra 罗 and sa 沙, the combined them with Chinese characters that approximates the meanings of the indigenous words (quickly, etc.): 速, 出 and 下.