Cludo Search is not a black box - the search relevance is based on a unique blend of machine learning and human customization.
1. Page rankings
Custom page rankings overrule all settings, controllable on a per query basis.
2. Machine Learning (intelligent rankings)
Automated intelligent rankings. Cludo learns and refines relevance over time on a per query basis. Essentially: the more clicks on a result, the higher the ranking, meaning that your users help improve your search result relevance over time.
3. Engines (boosting)
Automated rankings based on rules the administrator sets from Engine settings. Boosting lets you define sections of your site that should have a higher/lower priority amongst your search results.
4. Search Application
The search application, no rules applied, is based on the Okapi BM25 algorithm (BM=Best Matching).