Why it matters
A regional MRO house checks its share of AI answers for "food-grade lubricant supplier" style prompts month over month. It runs the prompts, records when its catalog gets named, and notes whether the mention is favorable or buried under a bigger distributor. Brand Radar is one instrument it uses for this, not the definition of the work. The point is the trend line: are we showing up more often this quarter than last, on the questions buyers actually type into an answer engine.
Keyword rank told you where you sat on a page of links. AI visibility tracking tells you whether the engine quotes you at all when a buyer asks for a NSF H1 grease cross-reference. That surface is where the click increasingly never happens, so not appearing there is invisible in your old analytics.
Tools vs the term
Vendors own the product names. Nobody owns the generic practice. Ahrefs Brand Radar, Profound, and Peec are instruments that sample engines and report mention and citation counts. The term itself is just the discipline of measuring AI answer presence, the same way "rank tracking" outlived any single rank tracker.
In practice
A hydraulics distributor defines 40 buyer prompts, from "replacement for Parker PV270 pump" to "best supplier for SAE J517 hose." It samples each across three engines weekly, because answers drift between runs. The dashboard shows mentions climbing on cross-reference prompts after a PIM cleanup, and flat on "best supplier" prompts where a national competitor still dominates. That gap becomes the next content target.