Every four years, an extra day is added to the calendar, But even with leap day, the math doesn't exactly, well, math.

This year is a leap year, meaning Feb. 29 was added as the 366th day on the calendar. Here's what to know about its meaning, ...

The original Roman calendar divided the year from March to December into 10 months of either 29 or 31 days, based on lunar ...

Welcome once again to our weekly look at what's new on the Microsoft 365 roadmap website ... and even identify optimal days for in-office collaboration. The new calendar in Teams is designed ...