'Today' is a compound noun formed from two characters: 今 (jīn), meaning 'now' or 'this', and 天 (tiān), meaning 'day' or 'sky'. Together, they literally mean 'this day', and function as a time noun indicating the current calendar day — from midnight to midnight. It’s one of the most frequently used time words in daily Mandarin and appears in greetings, schedules, weather reports, and personal plans.

Unlike English, Chinese doesn’t use articles before 今天, and it typically appears at the beginning or end of a sentence without prepositions. It can be modified by adverbs like 也 (also), 还 (still), or just (just now), but never takes measure words. While 今天 is neutral and appropriate in all registers — formal, informal, written, or spoken — it should not be confused with 今儿 (jīnr), a Beijing dialect variant used only in casual speech.