A single-server SharePoint Server 2010 environment leverages a built-in SQL Server 2008 Express database. The problems with this environment is scalability, not being able to install the with built-in database on a domain controller, the database cannot be larger than 4 GB, and you cannot use User Profile Synchronization in a single server with built-in database installation.

An example of a multiple tier FARM would be a three-tier topology, CONSIDERED one of the more efficient physical and LOGICAL layouts to supports scaling out or scaling up and provides better distribution of services across the member servers of the farm. This is considered a GOOD architecture since one can add Web servers to the Web tier, add app servers to the application tier, and add database servers to the database tier.

A single-server SharePoint Server 2010 environment leverages a built-in SQL Server 2008 Express database. The problems with this environment is scalability, not being able to install the with built-in database on a domain controller, the database cannot be larger than 4 GB, and you cannot use User Profile Synchronization in a single server with built-in database installation.

An example of a multiple tier farm would be a three-tier topology, considered one of the more efficient physical and logical layouts to supports scaling out or scaling up and provides better distribution of services across the member servers of the farm. This is considered a good architecture since one can add Web servers to the Web tier, add app servers to the application tier, and add database servers to the database tier.