A leap year is a year containing an extra day.
It has 366 days instead of the normal 365 days.
The extra day is added in February, which has 29 days instead of the normal 28 days.
Leap years occur every 4 years. 2016 is a leap year and so is 2020. Except that every 100 years special rules apply. For example 1900 was not a leap year, but 2000 was.
Plus there's a shiny new souvenir available this year from Geocaching.com!
This is just a small, informal gathering where you can come and meet some like-minded geocachers. If you're keen, there are barbecues if you want to cook some breakfast, and there's shelters, just in case it's raining.