Recreational use over rural land
In rural states with strong hunting, hiking, and ATV traditions, recreational use of unimproved land can ripen into a prescriptive easement if it is open, continuous, and adverse for the statutory period. The longer the period, the more a servient owner is protected — which is one reason the period is descriptive, not 'good' or 'bad.'
Permission defeats prescription
The single most important defense is that permission defeats the 'adverse' element. Granting written, revocable permission converts the use to permissive. Several states also let an owner post a notice that the use is by permission — Illinois (735 ILCS 5/13-122) is one example — which can stop the prescriptive clock.