Sharepoint Architecture Diagram (MOSS 2007 Architecture)
For understanding, What is Sharepoint?
Sharepoint is 3-Tier Application.
1. The Presentation Layer resides as .Aspx Pages (Asp.net Application)
2. Logic resides in .Net Assemblies.
3. Data resides in SQL Server Database.
Sharepoint is installed at "C:\Program Files\Common Files\Microsoft Shared\web server extensions\12", this root is popularly know as "12 Hive". You can find all resources related to sharepoint application here, which are prime focus to Developers.
MOSS 2007 Architecture Diagram