Understanding how web search engines work

We use web search engines on a daily basis, yet little is known about how they work. Search engines rank results according to algorithms that are not very transparent, and tend to highlight sites that are often commercial and not necessarily relevant.

How to optimize the quality of results? How can we better understand these ever-changing ranking algorithms? This fact sheet provides an overview of how web engines work, including :

• what they're really asking;

• what they don't know;

• the criteria they use to rank results.