SharePoint 2013 the New Continuous crawl

A new Crawl Option "Continuous crawls" has been Introduced in Search's Crawl Schedule category. Continuous crawls help to keep the search index and search results as fresh as possible.Continuous crawls run every 15 minutes by default although you can configure crawl schedules for SharePoint content sources so that crawls are performed continuously.Setting this option eliminates the need to schedule incremental crawls and automatically starts crawls as necessary to keep the search index fresh. Administrators should still configure full crawls as necessary.

When running, the crawler gets changes from SharePoint sites and pushes them to the content processing component.The document will get processed by the content processing component on the fly. No index has to be merged. Items appear in the search results right after they have been crawled.

Enabling continuous crawl has the following advantages:

• The search results are very fresh, because the SharePoint content is crawled frequently to keep the search index up to date.
  
• The search administrator does not have to monitor changing or seasonal demands for content freshness. Continuous crawls automatically adapt as necessary to the change rate of the SharePoint content.