What are @fn, @tel, @eml in the sql query below?

Question

Dear experts,

 

 

I would like to know what are @fn,@tel, @eml are ?

Are these names we just anyhow gave ?  If not where on earth it came from ?

protected void btnCreate_Click(object sender, EventArgs e)
        {
            DAO.MembersDAO memDAO = new DAO.MembersDAO();

            string sql = "INSERT INTO member VALUES (@fn, @tel, @eml)";

            //SqlParameterCollection spc = null;
            //spc.Add(new SqlParameter("@fn", SqlDbType.NVarChar)).Value = txtFullName.Text;
            //spc.Add(new SqlParameter("@tel", SqlDbType.NVarChar)).Value = txtTel.Text;
            //spc.Add(new SqlParameter("@eml", SqlDbType.NVarChar)).Value = txtEmail.Text;

            SqlParameter[] spa = new SqlParameter[3];
            spa[0] = new SqlParameter("@fn", SqlDbType.NVarChar);
            spa[0].Value = txtFullName.Text;
            spa[1] = new SqlParameter("@tel", SqlDbType.NVarChar);
            spa[1].Value = txtTel.Text;
            spa[2] = new SqlParameter("@eml", SqlDbType.NVarChar);
            spa[2].Value = txtEmail.Text;

            int result = memDAO.InsertMember(sql, spa);

            if (result == 1)
            {
                Response.Redirect("MemberList.aspx");
            }