The Content Search Web Part is a new web part in SharePoint 2013 that lets you bring together data from across SharePoint into a single view. For example, you might have a page on your intranet for engagements with a particular customer. You can use the Content Search Web Part to find any document that references that customer’s name and display it on that page, wherever the documents may be stored. Or you might have a web page with a web part showing which products are on special offer. The Content Search Web Part would let you pull results from multiple lists and display just those that match the query rules about the special offer. Or you could have a list of documents on the page that’s built based on who is viewing the page.
The queries that build these documents can be very simple (e.g. searching for a particular word), or very complex (e.g. a query searching for documents of a particular type, with particular properties, featuring certain keywords, filtered based on the user profile of the person viewing the page), or somewhere in between.
However the query has been built, the result looks to the user like a list of documents or list items, much in the same way as the web parts which let you display contents of a particular document library. The concept behind this is similar to the Content Query Web Part from SharePoint 2010. The difference is where the results are coming from. The Content Search Web Part lets you pull results from across sites to give a more comprehensive set of results.
When building one of these parts, you get nice tools like the preview of results so you can make sure your query is bringing back the results you expect before you put it onto the page.
Laura Rogers has written a post on configuring these web parts.