What is of this.Page.Controls.Add method in ASP.Net

sir what is the use of 

 this.Page.Controls.Add(SqlDataSource1);

in the following code.

  protected void ImageButton1_Click(object sender, ImageClickEventArgs e)
    {
        SqlDataSource SqlDataSource1 = new SqlDataSource();
        this.Page.Controls.Add(SqlDataSource1);
        SqlDataSource1.ConnectionString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
        SqlDataSource1.SelectCommand = "SELECT * FROM users WHERE ElectionId ='" + this.TextBox1.Text.Trim() + "'";
        this.GridView1.DataSource = SqlDataSource1;
        this.GridView1.DataBind();
        this.GridView1.Visible = true;
    }