The number of weeks in a year can vary depending on the calendar system used. The Gregorian calendar, which is the most widely used calendar in the world, has 52 weeks in a standard year and 53 weeks in a leap year. A leap year is a year that is divisible by 4 but not by 100, or a year that is divisible by 400. The year 2025 is not a leap year, so it will have 52 weeks.
The Gregorian calendar was introduced in 1582 by Pope Gregory XIII to correct errors that had accumulated in the Julian calendar, which was the calendar that was used previously. The Julian calendar had a leap year every four years, which caused it to drift out of sync with the solar year. The Gregorian calendar corrects this by having a leap year every four years, except for years that are divisible by 100 but not by 400.
