SharePoint : Index / Search Server
An Index Server is assigned the task of 'crawling' your content and building up an Index of key words and phrases. A Search Server then uses this index to respond to user searches and suggest results.
By pre-indexing content ahead of a search being performed results from a huge number (billions) of documents and web pages can be displayed extremely quickly. If the search was performed 'on demand' it could take hours for result to be collated. (This is exactly the same way that Internet search engines work).
In SharePoint you can have all services (web, database, index, search and application) on a single server in a small installation but indexing (and to a lesser extent) search services are often put on their own server. In a large installation you can have several index and search servers.
See Also
- Farm
- Application Server
- Index / Search Server
- Web Front End (WFE) Server
- Database Server
References
