Subject Matter Expert (SME)

Definition:

The Subject Matter Expert is that individual who exhibits the highest level of expertise in performing a specialized job, task, or skill within the organization.

An SME might be a software engineer, a helpdesk support operative, an accounts manager, a scientific researcher: in short, anybody with in-depth knowledge of the subject you are attempting to document. You need to talk to SMEs in the research phase of a documentation project (to get your facts straight) and you need to involve them in the technical validation of your drafts (to make sure that your interpretation of information matches theirs).