Declare ASP.NET Controls in web.config Instead of Individual Pages

Instead of declaring controls on individual ASPX pages, declare them once in web.config.

<system.web>
  <pages>
    <controls>
      <add tagPrefix="myCompany" src="~/ctl/usercontrol.ascx" tagName="MyControl"/>
      <add tagPrefix="otherCompany" assembly="OtherControlAssembly"/>
    </controls>
  </pages>
</system.web>