North vs. South (哪儿 vs. 哪里): In Northern China, especially around Beijing, `哪儿 (nǎr)` is the overwhelmingly common way to say “where” in daily conversation. In contrast, in Southern China, Taiwan, and Singapore, you will almost always hear `哪里 (nǎlǐ)`. `哪里` is also considered the more standard, formal, and “textbook” form used in written Chinese. While both are understood everywhere, using `哪儿` in Beijing makes you sound more local, while using it in Shanghai might subtly mark you as an outsider (though no one will mind).