What's the difference between "day" and "date"?

When used in reference to time, date almost exclusively refers to a specific 24 hour period that begins at midnight and ends at 11:59pm. When used this way, the date will be specified with a year (CE or BCE), the name of the month, and the number of the day within that month. The day number is a positive whole number that may be used in ordinal form (first, second, third, etc.) The name of the weekday is rarely referenced when referring to a date.

When setting up an appointment, you typically use the term 'date' if the appointment is a long time away or in a formal business setting. When making appointments with friends, especially if they are happening within one week's time, you would use the term 'day'.

You ask a friend "What day do you want to have lunch?" The receptionist at your doctor's office will ask you "What date would you like to have your next appointment?"

Date is a much more wide-ranging word. It can mean:

• A precise time (as you have said)
• A pre-arranged meeting (and as a similar verb - 'We're dating.')
• As a verb, to assign an age to something

Not to mention a few more archaic meanings.

And of course it's also a fruit!

a day is a constant while a date keeps on changing over time, for example Tuesday the 30th of December 2008 was on the fourth week. however,the fourth week of December 2011 presents us with a Tuesday with 27th as its date. this shows us that the day "Tuesday" continue to appear in fourth week, but with a different date. this then provokes the question why do people celebrate birth dates instead of birth days?