Metadata are Information contained within a badge that defines it:
Includes name, description, and links to other important details like the badge’s criteria, evidence and issuer information.
The metadata for an awarded badge is defined in a badge assertion.

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Badge Design Canvas is a useful instrument for designing open badges. It has been developed by DigitalMe in UK and can be downloaded here

Badge Earner is a person who has met the necessary requirements to earn a badge.

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Endorsers are organizations with the expertise to analyse the quality of specific badges, including how the badge is defined, the competencies it represents, its standards alignments, the process of assessing the badge earner, and the qualifications of badge issuer to structure and evaluate the learning achievement represented by the badge.

Digital Badges in Education: Trends, Issues, and Cases edited by Lin Y. Muilenburg, Zane L. Berge

A badge Issuer creates, offers, and awards badges. 

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The consumer is someone viewing a badge awarded to an earner. 

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