How a company maps every role onto a numbered ladder (L3, L4, L5, and so on), with each rung tied to a documented scope of impact and a pay band for salary and equity.
Google publicly defined an engineering ladder running from L3 (entry-level) through L10 (Google Fellow), with each level documenting scope (team, multi-team, org, company, industry), expected outputs, and base pay bands. Levels.fyi crowdsourced the comp data from current and former employees, and by the late 2010s most US tech companies had reverse-engineered their own ladders against Google's as the benchmark.