Allemansrätten

Allemansrätten is a Swedish term that translates to "Everyman's Right" in English. It refers to a right that has been established in a number of northern European countries known commonly as the "Freedom to roam".

The practice of roaming, and the right to do so, was something people just did without hindrance for hundreds of years before it became a codified, legally protected right in Nordic & Baltic countries such as Sweden, Norway, Finland, Estonia & Latvia, and other European countries such as Austria and Switzerland.

Of course, the right to roam does have a few limitations established by the particular country that one may chose to roam through- basically, a person can hike across (and even camp out for a night or two) undeveloped public or private lands without hindrance, but cannot make themselves a nuisance, and cannot encroach upon cultivated lands or areas that are fenced off or utilized by the government or private owners for specified activities (It's a long list determined by the governments of the various areas where roaming is allowed - you'll have to look it up for the area you're roaming in). 

As a rule, people are limited to hiking specifically  - can't drive an SUV or RV anywhere you want, gotta use the ol' heel-toe express exclusively.

The right to roam also extends to fairly unrestricted temporary use of waterways, beaches, forests, etc. "Temporary" is the key word here - nowhere can one erect a long-term shelter of any kind. 

There is also a long-list of responsibilities that go along with the right to roam - the old adage "leave no trace" sums the responsibilities up succinctly.

The concept of the freedom to roam does exist in other regions of the world, but it can be more limited, depending on the particular government (In England and some of the other Commonwealth countries such as Canada & Australia there is a "Crown Land" restriction that can be tricky to navigate). 

In the United States the right of way on private property is severely limited by trespass laws that literally have criminalized hiking - though not due to mean-spirited motivations on the part of the property owners themselves - the trespass laws are generally enacted due to the propensity of people who injure themselves on private property to seek legal redress (re: monetary compensation) for whatever injuries they suffered by suing the property owners, despite the fact that the property owners did absolutely nothing to invite the trespassers onto the property or cause the trespassers to injure themselves.

Which is why one sees "Posted: No Trespassing" signs all over the U.S.

Of course, approximately 640 million acres of land in the United States is considered public land, on which everyone has a right to roam similar to the European model. That 640 million acres is larger than the Nordic & Baltic countries combined, so it's not like there's nowhere to roam in North America. - if roaming is your thing, that is.