3. How are search results ranked by the engine?

When you launch a keyword query on a web search engine, you're usually presented with a large number of results ranked by relevance. The algorithm – a set of mathematical formulas – used for this ranking takes into account multiple criteria, which evolve over time. For example, Google's algorithm is based on no fewer than 200 criteria, and undergoes hundreds of modifications every year...

Each web engine has its own ranking algorithms and doesn't reveal all their secrets. We will, however, present the most important elements, common to most web engines (Google, Bing, Qwant...).

A distinction needs to be made between SEO (search engine optimization) and SEA (search engine advertising). Webmasters can use both approaches to reference their sites and guarantee good positioning in the search engine results. Sponsored links", placed at the top...