ASP.NET - Understanding Runat Attribute

The runat="server" attribute is used in ASP.NET web forms to indicate that a control should be treated as a server-side control, meaning that it can be manipulated by server-side code (such as C# or VB.NET) and can participate in server-side events and view state management.

When a control has the runat="server" attribute, ASP.NET generates server-side code for the control at runtime, which is responsible for rendering the control's HTML markup and handling any server-side events associated with the control.

Other possible options for the runat attribute in ASP.NET web forms include:

• runat="client": This attribute is used to indicate that a control should be treated as a client-side control, meaning that it can be manipulated by client-side code (such as JavaScript) but cannot participate in server-side events or view state management. This attribute is rarely used in ASP.NET web forms.
• runat="server" (default): This is the default value for the runat attribute in ASP.NET web forms, and is used to indicate that a control should be treated as a server-side control.
• runat="both": This attribute is used to indicate that a control should be treated as both a server-side and a client-side control. This is useful for controls that require both server-side processing and client-side interactivity, such as the ASP.NET AJAX Toolkit controls. However, this attribute is also rarely used in ASP.NET web forms.