The 100 essay questions have been reworded and are organised under common topics and essay types. IELTS often use the similar topics for their essays but change the wording of the essay question. In order to prepare well for writing task 2, you should prepare ideas for common topics and then practice applying them to the tasks given (to the essay questions).
You are required to speak to your examiners for about two minutes on any one of five topics. At the end of your presentation your examiners will start a discussion with you on the topic on which you have spoken, for about three minutes.