ORCID stands for "Open Researcher & Contributor ID".
ORCID is an open, non-profit group which provides a unique digital identifier that distinguishes you from every other researcher and, through integration in key research workflows such as manuscript and grant submission, supports automated linkages between you and your professional activities, ensuring that you get proper credit for all of your research.
There are many circumstances which make linking researchers with their research by name a challenge:
Unique author identifiers are the solution:
See: Research Profiles: A Tag of One's Own. "Digital identifiers can sort out different scientists with the same names, and create a lifelong record of their work."
Source: Ten things you need to know about ORCID (Impactstory blog, April 2014)
You can link your ORCID account with websites such as Scopus, Web of Science, Figshare, Impactstory, and PubMed's My NCBI. Once they're linked, you can push information back and forth between services.
For instance, you can import publications from databases like Scopus to help populate your ORCID profile. Then you can link your ORCID to your My NCBI account and make all your works that are not in PubMed easily available for inclusion in My NCBI's new SciENcv biosketch tool.