Thank you for using the Yahoo Term Extraction API. To help focus our efforts on core Yahoo! product experiences, we will discontinue direct access to the Yahoo Term Extraction API by September 28 2013 and will require developers to go through YQL. You can find more details at http://yahoo.tumblr.com/062813
Yahoo! Term Extraction API (September 28, 2013)
We are eliminating direct access to the Yahoo! Term Extraction API and as of September 28, will require developers to go through YQL. We encourage all existing users of the Term Extraction Legacy API to migrate to YQL requests by September 28. You can use the YQL forums for any questions you might have about migrating to YQL. If you are already using the Term Extraction API via YQL, you don’t need to take any action.