Architecture of SharePoint Development Platform
SharePoint uses List, Library, Content Type for Data Management in a SharePoint Web Application.
How SharePoint Code Deployed to SharePoint Web Application?
SharePoint websites are similar to ASP.Net websites as they are hosted in IIS. However There are differences in the process of code deployment. SharePoint code is deployed to SharePoint web application in the form of WSP (Windows Solution Package).
Visual Studio has the feature to make a wsp package. That WSP file can be deployed either by central admin UI or PowerShell Command.
Assembly Deployment (DLL)
There are 2 ways that a SharePoint Web Application can access assembly files.