Confluence can search content including pages, blog posts, emails, Microsoft Word documents and Excel spreadsheets, PDF documents, and more.
As well as using the search box at the top right of every Confluence page for ad hoc searches, you can use the 'Search' macro to embed particular search results in a particular page.
E.g. you could use the following code to find content that contains the word 'tutorial':
{search:tutorial}
... giving this: