Amazon listing optimization rests on two distinct disciplines: SEO, which pleases the A9 algorithm so the listing is found, and conversion optimization, which pleases the customer so the listing converts once found. Treating these as one problem, or skipping one for the other, is a common seller failure mode.
The A9 algorithm ranks listings primarily on two inputs:
Because keyword relevancy is the only lever a seller fully controls, keyword research becomes the highest-leverage starting point — see Helium 10 Cerebro and Reverse ASIN Lookup (Data Dive) for reverse-engineering workflows.
Quote: "SEO is all about pleasing the Amazon algorithm, and conversion optimization is all about pleasing the customer." / "you don't have full control over your sales, but you do have full control over your keywords."
"When bullet points are too long, it becomes a huge turn-off and shoppers are not going to spend the time to read it" — bullet length is treated as a direct conversion lever, not just a place to cram keywords.
General SEO refers to basic indexing — getting the listing to show up for relevant search terms. Effective SEO does that AND also drives click-through rate: the same keyword-placement decisions that earn indexing also need to be executed so shoppers actually click once they see the result. A listing can be fully indexed (good general SEO) yet still underperform if its title/images don't earn clicks. Most self-described "listing optimizers" only do the indexing half and skip the CTR half — see Six-Area Amazon Listing Optimization Framework.
'Effective SEO' is distinguished from plain 'general SEO': general SEO is keyword indexing only — making sure the listing shows up for the right search terms. Effective SEO goes further, choosing and placing those same keywords specifically to increase click-through rate once the listing appears in results (e.g., in the title and main image), not just to be found. In practice this means keyword placement decisions should be evaluated against both indexing value and their effect on how compelling the result looks, not indexing alone. See Main-Image CTR as the Highest-Leverage Controllable Growth Lever and A9 Title Keyword Weighting (Position & Phrase Match) for where CTR-oriented keyword placement matters most.