This application was originally designed to allow people to share their Trekking experiences, but it can be used to describe any journey someone might wish to share.
From a 1 hour walk, to an 8 day trek, to 5 day boat trip, to 30 day bus trip. Anything where you need to show photos in a geographical context essentially.
Whist it does show journeys from all over the world, that is not really that useful if you are looking for specific treks, so you can filter the journeys display to you based on country, region, type of activity, distance from you or some other location.
It presents journeys that have been published by their authors to all owners of the application, however authors can choose to keep their journeys to themselves until they are ready to share. There is no limit to where the journey maybe on the planet.
The overriding principle is that you can only edit things you have created. If you want to edit you will need an active iCloud account on your device.