Swedes have a word for freedom to roam. Wild camping is actively encouraged in Norway, where mountains rise and waterfalls thunder. Wild camping in Poland isn't legal, but it's widely accepted. Camping on the beach or in any national park is not recommended.
Popular hiking destinations, such as the Tatra National Park, are especially strict about this and are monitored by park rangers. In just about any national park, you'll most likely end up with a fine. Oddly enough, you're not actually legally allowed to camp in a forest, but from what we've read, that's pretty much only true if you're planning on having a campfire. If not, you're ready, even the official Polish forest office has a map with forests and sites that are good for camping.
Northern Europe is usually very suitable for camping in the wild. There is only one country in Northern Europe where wild camping is not legal, Denmark. But even Denmark offers plenty of alternatives. Certain countries in this part of the world not only legally allow wild camping, but they even encourage it.
Scandinavia (except Denmark, see below) is probably an absolute paradise for many wild campers. With dozens of trips under her belt, Diane is an expert at minimalist camping, using little luggage, planning and keeping her children entertained without screens. Campfires are not allowed in places where there is a risk of fire, such as in areas prone to wildfires or without sufficient firewalls, or near structures built with combustible materials. Camping in the middle of nature in Estonia is almost as easy as in the Nordic countries mentioned above, and Estonia also has the “right to roam” law, which grants the right to camp and hike freely in nature.
So make sure to bring a camping bag instead of a real tent if you're planning to camp in Germany in the wild. I wrote a full article about wild camping in the UK for those of you who want to know more about the topic. However, one problem that does exist in the Mournes is that, due to their accessibility, young people often leave behind a considerable amount of garbage and damage. If you were thinking of camping in the Slovak part of the Tatra Mountains, you should know that this is not legally allowed.
That said, Bulgaria recently added a new law that explicitly prohibits camping outside of camping sites. Apparently, there are certain protected areas where it's illegal to camp in the wild, but other than that, you're ready to go. National legislation states that it is allowed to do so if certain rules are followed; camping is not allowed less than 100 meters from the sea, national and natural parks are prohibited, private property is prohibited, this includes historic monuments, military zones and urban areas are illegal. Armenia, Georgia, Belarus, and Moldova are countries that don't really have laws against wild camping, so you can camp pretty much anywhere you want; with the exception of a few national parks.
One thing I wanted to mention is that Cypriots don't care much about camping in the wild, but they do care that they light a campfire during the hottest months. Located off the north-west coast of Scotland, the remote Hebrides are full of spectacular wild camping spots. I can't imagine this being strictly enforced, but keep in mind that you shouldn't stay too close to the roads if you want to camp in France. There are practically no restrictions on camping in the wild in Kosovo and there are many beautiful places to camp in the wild in Kosovo.
I repeat, this isn't camping in the wild, but it's not camping in a camp with other people around either...