日 (rì) means sun, day, or date. In formal and written Mandarin it is the literary word for day (明日, tomorrow; 每日, every day; 假日, holiday) and is the standard word for the date (几日, what date). 日 is also the short form for Japan (日本 Rìběn, abbreviated 日). In compounds it covers daytime (日间, daytime), diary (日记), and calendar (日历). In casual spoken Mandarin 天 (tiān) is more common for day, while 日 sounds more formal.