There has been an ongoing debate in the healthcare community about what pressure ulcers/injuries are, and how to name, define and classify them. The aim of this discussion paper is to provide a brief theoretical background about pressure ulcer/injury classification, to explain the approach the Guideline Governance Group has taken during the 2019 update of the International Guideline for 'Prevention and Treatment of Pressure Ulcers/Injuries' and to share views on how to best implement pressure ulcer/injury classification. First formal pressure ulcer/injury classifications were introduced in the 1950s and today various pressure ulcer/injury classification systems are used worldwide. Dissimilarities between commonly used classification systems may be considered a limitation that impedes clinical and scientific communication. However, the conceptual meaning of pressure ulcer/injury categories described within the various classification systems is comparable and the current evidence does not indicate that one classification is superior to another. Therefore, the Guideline Governance Group created a crosswalk of the major pressure ulcer/injury classifications in common use across different geographic regions. Clinicians are encouraged to use the classification system adopted by their healthcare setting in the most consistent way. The validity of pressure ulcer/injury classification is closely linked to its intended purpose. Studying measurement properties of pressure ulcer/injury classification systems must follow state-of-the-art methods. Structured educational interventions are helpful for improving diagnostic accuracy and reducing misclassification of pressure ulcers/injuries. Implementation of innovative skin and soft tissue assessments and revised pressure ulcer/injury classifications are only worth implementing, when the diagnostic information improves clinical care.