An advisor is an outside expert who provides part-time strategic guidance, introductions, or domain expertise to a startup in exchange for equity. The relationship is formalized in a short advisor agreement and distinct from board members (advisors have no fiduciary duty and no voting power), from investors (advisors are not buying equity), and from consultants (advisors are ongoing relationships paid in equity, not project work paid in cash). The role is the most common way founders extend their leadership reach in the first three to four years of a company.
The categories that matter: technical advisors (a senior engineer or domain expert who reviews architecture decisions or vouches for the founders to investors, typically 1 to 4...