SharePoint Servers

SharePoint : Farm
A Farm or Server Farm is a group of servers that share the same administrative tools and are part of the same organization or group.

It can be done (web/datababase/index etc) on a single server in “Simple Installation” mode in which case you don’t need a NLB. For many small businesses this is plenty enough. Medium sized businesses usually start with at least 2 Web Front Ends (WFE’s) and a database server. Multinationals can have some very complex setups involving dozens of components.

SharePoint : Web Front End server (WFE)

A web server that handles web page requests from users, processes the request and returns the data. They process HTTP/S traffic and rely on Internet Information Server (IIS) to provide much of the web server 'stack'

In a farm there can be multiple Web Front End (WFE) servers and a Network Load Balancer (NLB) will distribute requests between them. This is the primary method of scaling in SharePoint - as the number of users grows you add more WFE servers. Is also used to add redundancy - If a WFE fails the NLB can distribute requests to other WFE's.

SharePoint : Application Server

An Application Server is a computer that provides key infrastructure and services for applications that are hosted on a farm.

Typically - in SharePoint this means that a server that has been assigned to run duties such as Excel, Visio or Access Services or Index/Search services - as opposed to general web server duties of a Web Front End server.

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.