Using HttpWebRequest in C#

Uri address = new Uri("http://api.search.yahoo.com/ContentAnalysisService/V1/termExtraction");

            // Create the web request
            HttpWebRequest request = WebRequest.Create(address) as HttpWebRequest;

            // Set type to POST
            request.Method = "POST";
            request.ContentType = "application/x-www-form-urlencoded";

            // Create the data we want to send
            string appId = "YahooDemo";
            string context = "Italian sculptors and painters of the renaissance"
            + "favored the Virgin Mary for inspiration";
            string query = "madonna";
            StringBuilder data = new StringBuilder();
            data.Append("appid=" + HttpUtility.UrlEncode(appId));
            data.Append("&context=" + HttpUtility.UrlEncode(context));
            data.Append("&query=" + HttpUtility.UrlEncode(query));

            // Create a byte array of the data we want to send
            byte[] byteData = UTF8Encoding.UTF8.GetBytes(data.ToString());

            // Set the content length in the request headers
            request.ContentLength = byteData.Length;

            // Write data
            using (Stream postStream = request.GetRequestStream())
            {
                postStream.Write(byteData, 0, byteData.Length);
            }

            // Get response
            using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)
            {
                // Get the response stream
                StreamReader reader = new StreamReader(response.GetResponseStream());

                // Console application output
                Console.WriteLine(reader.ReadToEnd());

            }