Answer:
   The word 'talmud' literally means 'study'. The Talmud is sometimes
   referred to as the Shas. Shas is a shortened form of the term 'Shisha
   Sedarim (six orders), a reference to the six orders of the Mishna.
   There are two distinct works known as Talmud: the Yerushalmi
   (Jerusalem or Palestinian) Talmud, and the Bavli (Babylonian Talmud).
   However, the Babylonian Talmud has greater popularity and authority,
   so the generic term 'Talmud' almost always refers to the Babylonian
   Talmud. The generic 'gemara' thus refers to the gemara of the
   Babylonian Talmud. References to the Jerusalem Talmud are explicitly
   qualified.
   
   Traditionally, the Talmud is the supreme sourcebook of Law, as it
   takes the rules listed in the Torah and describes how to apply them to
   different circumstances. Although technically not a legal code (other
   works were created for that purpose), it is the ultimate source
   material that is used to decide all matters of Halakha (Jewish law).
   
   Traditional rabbis study the Talmud in depth; however, they use the
   actual Talmud very rarely, preferring to accept opinions in later law
   codes as binding. Study of Talmud for its own sake is considered a
   great mitzvah.
   
   Conservative rabbis also consider Halakha as binding, but do not
   always accept the most recent and stringent opinions in the latest law
   codes as absolutely binding; As such they use the Talmud in the same
   way that rabbis of past eras used to use it. This is theoretically
   still an option in the Orthodox community, but in practice is used
   very rarely.
   
   Reform and Reconstructionist Jews do not teach Talmud in their Hebrew
   schools, but do teach it in their rabbinical seminaries. This material
   is used as part of the research into the application of Torah law, but
   the research also includes study of the larger context of the time,
   and the parallels to other co-existant societies.
   
   A citation "Check the gemara, Yevamos 12b" means tractate Yevamos,
   folio 12, reverse side of the folio as per the organization of the
   Vilna edition of the Babylonian Talmud. Similarly, Chullin 5a would be
   the obverse side of the fifth folio of tractate Chullin. "Daf Yomi" is
   a program in which the participants study both sides of a folio of the
   Babylonian Talmud every day of the year. It takes about 7.5 years to
   complete the cycle.
   
   After the closing of the Talmud, there has been considerable further
   development of the Law in the areas of practical application, but
   always in a tone that reveres the stated views of the Talmudic rabbis
   as being on a higher plane than those of our modern scholars, who are
   free to interpret but not to contradict. A sharp distinction is always
   drawn between Torah Law (meaning law that derives directly from
   prohibitions in the Written or Oral Torah) and Rabbinic Law (meaning
   law that the Talmudic rabbis adopted as a `fence' to protect us from
   unwarily transgressing Torah Law), and different standards are used to
   judge cases of doubt in matters of Torah Law than of Rabbinic. Often,
   a false distinction is made by uninformed posters between `Torah'
   (meaning Written) Law and Oral Law---in traditional Judaism, the two
   stand together in distinction to Rabbinic Law. Example: the Written
   Law says `an eye for an eye'. The Oral Law says (and historical
   documents from the Second Temple era confirm) that this was _never_
   intended literally, but rather means `measured and just (monetary)
   compensation for damages inflicted'. The Rabbinic Law upholds this
   principle, but might still command a man to forego the monetary
   damages in certain cases so as not to even come close to transgressing
   some other Torah prohibition, such as exacting interest on a debt, or
   causing baseless hatred. The first two are Torah, the last is not. But
   all are binding on Jews worldwide. (Note: A still lower level of
   `law', called minhag, or `custom', is post-Talmudic and usually has
   force only within particular communities.)