<asp:TextBox ID="txtEmail" runat="Server" Columns="40" />
<asp:RegularExpressionValidator ID="revemail" runat="server" ControlToValidate="txtEmail" ErrorMessage="Eg:abcde@abc.ad" validationexpression="^.+\@.+\..+$"  Display="static" SetFocusOnError="true"></asp:RegularExpressionValidator>

<asp:TextBox ID="txtPincode" runat="Server" Columns="40" />
<asp:RegularExpressionValidator ID="revPincode" runat="server" ControlToValidate="txtPincode" ErrorMessage="enter correct pincode" validationexpression="^.+\@.+\..+$"  Display="static" SetFocusOnError="true"></asp:RegularExpressionValidator>

<asp:TextBox ID="TextBox3" runat="Server" TextMode="Password" Columns="40" />
<asp:TextBox ID="textbox2" runat="Server" TextMode="Password" Columns="40" />
 <asp:CompareValidator ID="CompareValidator1" runat="server" ErrorMessage="Passwords don't match!" ControlToValidate="TextBox3" 
        ControlToCompare="textbox2" ></asp:CompareValidator>

<asp:TextBox ID="txtValidityDate" runat="server" />
 <asp:RegularExpressionValidator ID="revvaliditydate" runat="server" ControlToValidate="txtValidityDate" ErrorMessage="Date Format(dd/mm/yyyy)" 
                            ValidationExpression="^(((0[1-9]|[12]\d|3[01])\/(0[13578]|1[02])\/((19|[2-9]\d)\d{2}))|((0[1-9]|[12]\d|30)\/(0[13456789]|1[012])\/((19|[2-9]\d)\d{2}))|((0[1-9]|1\d|2[0-8])\/02\/((19|[2-9]\d)\d{2}))|(29\/02\/((1[6-9]|[2-9]\d)(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00))))$" Display="static" SetFocusOnError="true"></asp:RegularExpressionValidator> 

ValidationExpression="(^\d{3}\-?\d{2}\-?\d{4}$)"     

ValidationExpression="(^((\(?\d{3}\))|(\d{3}))?\s?\d{3}[\-.]?\d{4}$)"