One year consists of 12 months, and usually lasts 365 sidereal days. A sidereal year is the time when the round takes a complete turn around the sun.
There are different types of year, which have been adopted by various cultures through the ages, among them: The sidereal year, the solar year and the calendar year, which is used for the measurement of religious holidays.
Astronomers discovered after several studies that during a period of every four years 366 days are counted, and this year it is called a leap.
(See also how many weeks are in a year exactly).
Every year is exactly 365 days, 5 hours, 48 minutes and 46 seconds. This is why exist normal years and leap years
One normal year has 365 days. The year is divided into 12 months, which have 30 or 31 days, except February that has 28.
One leap year has 366 and it occurs every four years (see more about why is there a leap day and when is the next leap year) The year is divided into 12 months, which have 30 or 31 days, except February that has 28.
If you don’t want to count weekends then the number of days is 261 = 365 – 104 (number of Saturdays and Sundays).
On other planets
687 days which is the mars orbital period around the sun.
225 days which is the mars orbital period around the sun.