Is there really only 364 days in a year?

No, there are actually 365 days in a year in the Gregorian calendar, which is the most widely used calendar system in the world. This calendar accounts for the time it takes for the Earth to orbit the sun, which is approximately 365.24 days. To adjust for this extra fraction of a day, we have a leap year every four years with an extra day added in February, making it a 366-day year.

The earth takes 365.2425 days to orbit the sun, a regular year is 365 days, so to make up the shortfall a day is added every four years to reset the datum, otherwise the seasons would shift out of line with the calender.