About this library
The Reference is a library for the people who plan, buy, measure, and regulate digital advertising, and for anyone trying to understand what those people are talking about. It lives on agencyechelon.com and is written by the people who run the agency.
What it is
A glossary of the trade's vocabulary, profiles of the platforms where money is spent, benchmark ranges with their sources, ad specs, comparisons, calculators, the standards the pipes run on, the rules that constrain the whole thing, and a neutral directory of the companies involved. Entries are written to be precise enough for a practitioner and plain enough for a newcomer, and to be quoted by a person or a language model without distortion.
What it is not
It is not a blog, a newsletter, a course, or a lead magnet. There is no email gate, no sponsored placement, no affiliate link, and no advertising of any kind inside the Reference. The agency's own writing lives in The Signal, and when a post uses a term defined here, it links here.
Who maintains it
Agency Echelon, a digital advertising and paid media consultancy in the Washington, DC area, writes and reviews the entries. The same team maintains free public registers of AI regulation, crypto regulation, and data privacy law, plus a third-party audience finder and an ad mockup generator.
Editorial standards
Facts that change are dated. Numbers that vary are given as ranges with sources. Vendors are described, not rated, and the description is what the company does, not what it says about itself. Where the industry disagrees, the disagreement is stated. Drafting uses AI tools; every entry is reviewed and edited by a practitioner before publication, and the review date on each page is a human review date.
Corrections
Errors are fixed when reported with a source. Write to info@agencyechelon.com.
Reuse
Text is licensed under Creative Commons Attribution 4.0. Quote it, teach from it, cite it. Each entry carries a suggested citation. Machine-readable copies of the glossary and platform profiles are at /data/glossary.json and /data/platforms.json, and /llms.txt describes the site for automated readers.