日期 (rì qī) is the general noun for a calendar date (e.g., 'What's today's date?'). It's more specific than 日子 (rì zi), which can also mean 'daily life' or 'day' in a broader sense. Unlike 日 (rì), which is used in fixed expressions like 生日 (birthday) or written contexts, 日期 is the everyday word for a specific day on the calendar.