Place a comma between the day and the year. Example: We celebrated with fireworks on July 4, 2010.
Place a comma after the year if the sentence continues. Example: We celebrated with fireworks on July 4, 2010, when he came home from Iraq.
Place a comma after the day of the week, if it is known. Example: Today is Wednesday, May 11, 2011.
Do not use commas when only the month and year are mentioned. Example: We celebrated in July 2010 when he came home.
Use an apostrophe to indicate a decade or a year of graduation. Example: She was born in the '90s.