iam getting an error as"An exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll but was not handled in user code
Additional information: Incorrect syntax near the keyword 'user'.
how to rectify the error.....! 
 
 
using System.Data.SqlClient;
 namespace emp
 {
     public partial class details : System.Web.UI.Page
     {
         SqlConnection con = new SqlConnection("Data Source=SRINU-PC\\sqlexpress;Initial Catalog=register;Integrated Security=True");
         protected void Page_Load(object sender, EventArgs e)
         {
          }
          protected void Button1_Click(object sender, EventArgs e)
         {
             con.Open();
             SqlCommand cmd = new SqlCommand("insert into user values ('" + TextBox1.Text + "''" + TextBox2.Text + "''" + TextBox3.Text + "''" + TextBox4.Text + "''" + TextBox5.Text + "')", con);
             cmd.ExecuteNonQuery();
             con.Close();
             Label1.Text = "Values are Inserted";
         }
     }
 }