Answer:
   
   The Talmud Yerushalmi, also known as the Jerusalem Talmud (JT), the
   Palestinian Talmud, Talmud Eretz Yisrael (Talmud of the Land of
   Israel) and Gemara de Eretz Yisrael, is the Mishna plus the Yerushalmi
   gemara. It is interesting to note that the JT that we have today is
   missing a huge amount of material. There is only commentary for the
   first four orders of the Mishna; The rest has been lost to history.
   The JT gemara is also missing for tractates Avot and Eduyot, parts of
   Toharot and other sections as well. Despite extensive scholarship, it
   still is unclear why this material was not included in the final
   redaction of the JT.
   
   Rabbi Yohanan bar Nappaha was the main redactor of the JT. It was
   redacted around 500 to 550 CE. Additionally, the name 'Jerusalem
   Talmud' is a misnomer; it was most likely written in Northern Israel,
   specifically Tiberias.
   
   In general, whenever the JT contradicts the Babylonian Talmud (BT),
   the law follows the BT. Only on matters where BT is silent or unclear
   does the authority of the JT prevail.
   
   The absence of numerous Mishna tractates and chapters, the numerous
   self contradictions, as well as other internal evidence, suggests that
   the JT was not in fact redacted in the proper sense of the word, but
   rather was a hasty collection of material. Many scholars believe that
   the reason for the ultimate acceptance of the BT rather than the JT
   had a lot to do with the power struggles between the two Jewish
   communities. Thus it can be argued that the poor preservation of the
   JT may be a result of its rejection rather than its cause.