Most interactions with Solr, including indexing and searching, are processed by what Solr calls request handlers. Request handlers are configured in the solrconfig.xml file and are clearly labeled as such. Many of them exist for special purposes, such as handling a CSV import, for example. Here is how the default request handler is configured:
<requestHandler name="/select" class="solr.SearchHandler">
<!-- default values for query parameters can be specified, these will be overridden by parameters in the request -->
<lst name="defaults">
<str name="echoParams">explicit</str>
<int name="rows">10</int>
<str name="df">text</str>
</lst>
… The request handlers that perform searches allow configuration of two things:
Establishing default parameters and making some unchangeable
Registering Solr search components such as faceting and highlighting