[1/2] I think there is an important concept of Mandarin that should be clarified. It is "character". "Character"(字, not letters) is not a concept exclusive to Mandarin, but rather for all Sino-Tibetan family languages. But in most languages of this family, "character" is an abstract concept only, with no need to be physical. It means that characters are in the mind of every native speaker, even if that language has no written form. We will explain it in detail, using Mandarin as the example. However, it's the common law of the Sino-Tibetan family of languages. We all know that characters are the basic elements of the meanings of Mandarin. So we could write such a poem: 孤古固（孤独自古以来就固然存在） 故孤咕（所以我才发出咕咕声咏叹） 顾蛄孤（看到蟪蛄孤单渺小的样子） 故辜古（我就想一改古人对其看法） 蛄固孤（蟪蛄的声音固然孤寂弱小） 姑骨固（姑且其骨气还算坚定不移） 孤顾谷（我看着地上散落的麦谷子） 估蛄故（大概是蟪蛄遗留的精神吧） 故孤鼔（所以我鼓起肚子大吃起来） If you put it in the Google Translator, it would give you the pinyin: "Gū gǔ gù gù gū gū gù gū gū gù gū gǔ gū gù gū gū gǔ gù gū gù gǔ gū gū gù gù gū gǔ". Yeah, all are "gu". Don't read it to any native speakers, no one could understand it. But if you tell the native speaker what every character is, they could understand the meanings. As you see, unlike in most languages in the world, the meaning of Mandarin is by characters, not by sound. So, in everyday life, sometimes we should explain which the exact character is. Otherwise, the listener couldn't understand. Just like in English, we should explain which the word is, for example, "mail" or "male", although it's only in rare cases in English.