Best solution to store DateTime in a database? [on hold]

I'm in the middle of developing an application that requires storing date/time data. I would like to know what best practices there are for storing date time data in a db under the following requirements:

• The stored format of the date time should be time zone independent
• The stored format of the date time should be language agnostic

I would also like to know what is the data type of this stored date/time? Should it be an Integer? a String? A datetime?