Now that we have populated our data with four different cores, we can then use them to introduce the concept of distributed search.

A distributed search is a search that can be sent to a Solr instance, but will be actually executed while distributing queries over some different instances (and cores). This is generally intended to be used on a single schema definition that can be seen as a sort of very huge index, split for convenience on different parts (shards), on different Solr instances and cores.