This Practice Note explains the concept of negative prescription and positive prescription under Scots law, focusing on the five year negative prescription (or short negative prescription) and 20-year negative prescription (or long negative prescription) periods as provided for in the Prescription and Limitation (Scotland) Act 1973 and as amended by the Prescription (Scotland) Act 2018. It also considers some other negative prescriptive periods (such as for joint wrongdoers in contract and delict and in consumer protection). It covers imprescriptible obligations and offers guidance on key prescription concepts including calculation of the prescriptive period, the appropriate date in short negative prescription, suspension of the short negative prescriptive period due to fraud, error and legal disability, interrupting the prescriptive period with a relevant claim or relevant acknowledgment and the burden of proof where a question of prescription arises.