 In terms of the actual length of the Gemara, Avodah Zarah is fairly close to the middle, being an "average" length tractate.A brief list of major topics in each chapter follows.Since the chief aim in the Gemara is to explain and comment on the Mishnah, this is implied, and the topics mentioned will be ones that aren't directly about the Mishna (as a commentary is extremely difficult to summarize in a few lines).