A web directory is a human-curated list of websites sorted into categories by topic, industry, or region. Unlike a search engine, an editor decides what gets listed and where, which makes a directory closer to a library card catalogue than to an algorithm-driven index.
A search engine crawls the web automatically and ranks pages using hundreds of relevance signals. A directory is maintained by people, so its listings are static, sparse, and slow to update. The Open Directory Project (DMOZ) was the best-known general example until it shut down in 2017; niche and regional directories still operate today.
Most general-purpose directories now carry little ranking weight, and low-quality ones can look like link spam. The exceptions worth pursuing are trusted, moderated, and relevant to your niche or location, such as a regional business directory or an industry association listing.
A Toronto physiotherapy clinic submitted to 40 generic "free directory" sites and saw no movement at all. After dropping those and listing instead in the Canadian Physiotherapy Association directory plus two vetted local business hubs, its citations became consistent and its local pack visibility improved within roughly two months.