This document discusses the need for unique and persistent identifiers for researchers to help link them to their professional activities and contributions over time. It notes that relying solely on author names is inadequate due to common names, name changes, and variations in how names are written. It then introduces ORCID as a solution that provides identifiers that can be integrated into research workflows and systems to enable the interoperable exchange of information about researchers and their work. Finally, it provides an overview of ORCID's growing membership and international usage.