I'm new to custom server controls and I'm hoping to use them to build various 'modules' for different sites I build to cut down on duplicate code.
I'm familiar with custom user controls in which I can create an .ascx & .ascx.vb file which can then be imported into an .aspx page and used freely.
However, with custom server controls I cannot find a way of using markup/html code. Is this possible at all or must all code be created programmatically?
There is no designer support with Custom Controls.
See this support article to decide between two:
Overview of user controls vs. custom controls http://support.microsoft.com/kb/893667