I tend to see it a lot in text books and guides: 唱歌/唱歌儿 事/事儿 But it's always listed as optional, so what's the deal with it?
Adding the 儿 to the end of a word is known as 儿化 (er2hua4). Whether or not you use the 儿 really just comes down to regional accents/dialects, but the meaning of the word is unchanged. Generally speaking, northern mandarin dialects use the erhua more than southern ones; in some regions you'll almost never hear anyone use the erhua in speech.
There are some words where the added erhua changes the word's meaning, but these are usually regional/colloquial terms, such as 天儿, which means the same as 天气, not 天.
Erhua might differ in various dialects. Below I use Beijing dialect for example:
Erhua is hard to master, even for me(native southern Chinese). Sometimes I think it's unnecessary because the even the local might be wrong, but the wrong could be the right if everyone uses the wrong way.
- Meaning Difference. Put a 儿 after a word could have different meaning:
「宝贝」和「宝贝儿」: the First one normally mean a precious item, the later one usually mean close people, like lover.
「汆」和「汆儿」: the First one mean a way to cook; 「汆儿」 usual means the marinade for dry noodle b.
- Part of speech Difference:
Verb -> Noun
托 → 托儿 | 乐 → 乐儿 | 约会 → 约会儿
Adjective -> Noun
亮 → 亮儿 | 空 → 空儿 | 好 → 好儿
下 → 下儿 | 摊 → 摊儿 | 拨 → 拨儿
门 → 门儿 | 桌 → 桌儿 | 道 → 道儿
- Show Emotion
命 → 小命儿 | 灯笼 → 小灯笼儿 | 剪子 → 小剪子儿 | 镜子 → 小镜子儿 |发小 → 发小儿 | 家雀 → 家雀儿 | 心肝 → 心肝儿
光棍 → 光棍儿 | 小偷 → 小偷儿 | 傻冒 → 傻冒儿 | 白丁 → 白丁儿 Bad place or bad thing, like "Death死", there are several saying to 玩儿完了|蹬腿儿了|翻白眼儿了|嗝儿屁了|嗝儿了|