From FMOTL Wiki
A principle at law whereby certain rights and duties may be created or extinguished by having them written in or out of the law and having the subsequent state of affairs subsisting for a "prescribed" period. The term is often used in the context of a statute of limitations which exist in most jurisdictions placing time limits to the exercise of rights and enforcement of obligations.
The principle has a wide scope affecting not only property but rights and obligations in general. The jurisdictions specific statute of limitations will provide the time limits for various different interests. For example, in Scotland, an unchallengable right to an interest in a salmon river may be created over a period of 20 years according to the Prescription and Limitations (Scotland) Act 1973. That same statute of limitations provides a 10 year prescriptive period for an interest in land which is registered or recorded with the land registry. The same principal of prescription applies to claims for damages in cases of defective goods or industrial accidents.
The creation of rights and/or obligations.
Under positive prescription, a right or obligation is deemed to unchallengably exist after it has been exercised or complied with for prescribed amount of time. In such a fashion, a "right of way" may come into existence, creating not just a right for those who wish to exercise the right of way, but an obligation on the land owner to acknowledge the right of way should it be exercised for a long enough period. Until the prescribed period passes, the right or obligation may be judicially challenged by anyone having an interest. After the prescribed period has elapsed, the right or obligation is presumed to exist and cannot be challenged. The time taken for any right or obligation to become so unchallengable.
The extinction of rights and/or obligations.
Under negative prescription, a right or obligation which unchallengably exists may be extinguished if it has not been exercised or subsisted, has not been acknowledged and has not had a claim made in its favour for a prescribed period. Many jurisdictions will not recognise that a right will prescribe simply by inactivity.