Fusion is a search application development platform whose core is the Solr open-source search engine. These core concepts can help you get started:
A Collection is a Solr dataset that is managed by Fusion. It may include multiple datasources, but all of its data is queried as a single set.
Fusion’s components work together on a single host or in a distributed environment.
A flexible range of deployment types provide scalable, high-availability search.