Logical and Physical Architecture of SharePoint

In this article we will discuss about logical and physical architecture of SharePoint 2010.
Here are the common servers available in the SharePoint farm.

Front-end web servers: These servers responsible for publish web sites which are called as web applications.

Application servers: These servers host back-end services, such as the search index service, the crawler service etc.

Database servers:These servers store configuration and content data for the entire SharePoint farm.

A single tier deployment is something like the farm which is build based one single server only.
A two tier deployment is something like: It should have two front-end web servers and a back-end database server.One of the Web servers hosts the Central Administration site and the other handles additional farm-related tasks, such as serving content to users.

And a 3 tier farm has many dedicated application servers.

SharePoint always use a Microsoft SQL Server database for storing farm configurations and content. It creates a main and fundamental farm configuration database as soon as you deploy a new farm. Usually this database is called SharePoint_Config or SharePoint_ Config_<UniqueId>.