Posting a form data using Enter key in Asp.Net using Single submit Button

If we have few Textboxes and one Submit Button then add the Defaultbutton property in the form tag and assign the button id to Defaultbutton property as like below:-

<form id = "frm" runat = "server" defaultbutton = "btnSubmit">
<div>
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

<asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>

<asp:Button ID="btnSubmit" runat="server" Text="Submit" OnClick="btnSubmit_Click" />
</div>
</form>