Asp.net control development and learning (1)

When learning the Asp.net control development basics of clingingboy (1 ),
Http://www.cnblogs.com/Clingingboy/archive/2006/07/30/463471.html

When using controls

(1). Register it first.

<% @ Register tagprefix = "Custom" namespace = "customcomponents" %>

(2) Use tags to output results.

<Custom: creditcardform1 runat = "server" id = "CCF"/>

This method cannot be used normally in vs2005sp1, and the system prompts that the error cannot be found.

Then
In web. config
<Pages theme = "Maxthon">
<Controls>
<Add tagprefix = "data" namespace = "wxy. nettiers. Web. Data" assembly = "wxy. nettiers. Web"/>
<Add tagprefix = "data" namespace = "wxy. nettiers. Web. UI" assembly = "wxy. nettiers. Web"/>
<Add tagprefix = "wxy" namespace = "wxy. Web. webcustomcontrol" assembly = "wxy. Web. webcustomcontrol"/>
</Controls>
</Pages>
The above yellow sentence can finally be used. I don't know why