Enterprise search - what is it?

Search for inside a company rather than the web. One search box that looks through the intranet, shared drives, email, the CRM, tickets and so on, so staff can find a document without knowing which system it lives in. The hard part isn't the searching, it's permissions - it has to only show you things you're allowed to open. Not related to SEO, despite the name coming up in SEO tool lists sometimes.