What role do rabbis play in Jewish society?

Answer 1

Rabbi literally means teacher. "Rabbi" is not mentioned anywhere in The Bible.
In ancient times, rabbis emerged from the sages - ancient scholars in the late temple period who formed the sanhedrin - which was sort of a government.
Over time, rabbis roles evolved. Today they act as religious leaders of communities/congregations as well as teachers.
Rabbis are not "in charge" of Judaism, nor are they required to lead prayer or other rituals (any competent adult can do so).
Rabbis may also act as judges in a "beit din" - a religious court which can adjudicate issues of civil and family law in many countries, provided both parties agree beoforehand.

• Answer:
  

The above answer contains a number of errors according to our tradition.
1) Rabbis are indeed mentioned in the Tanakh (Bible), whether or not that same word is used. These, for example, are the Elders mentioned in Exodus ch.5 and Numbers ch.11. Those weren't simply old men; they were the elder sages (Rabbis) of their time.
2) The Rabbis didn't "emerge" from the sages; they are one and the same thing. Various titles have been used through the generations, but a Rabbi/sage has always been the same thing: a person who is foremost in Torah-scholarship and piety, who guides his congregation or the entire nation in matters of Torah-observance and living as a Jew.
3) The Sanhedrin did not form in the late Temple period. The Sanhedrin is mentioned over 400 years before that, as Sisinnes the Persian governor says he assisted the "leaders of the Sanhedrin" in building the Temple (Josephus, Antiquities 11:4). But the Sanhedrin itself is actually nothing other than the identical body of elders who existed from the earliest times.
4) the central roles of Rabbis are what they always have been.
5) Rabbis are indeed "in charge" of transmitting and interpreting Torah-law. Judaism wouldn't be around today if it weren't for the sages of Yavneh, the Talmud-sages of Sura, etc.
6) Not every Rabbi can act as a member of a Beit Din. A special level of expertise is required for that.

Answer 2

The role of a rabbi is to teach Torah, to guide the community, sometimes to settle disputes, sometimes to render decisions in Torah-law, and in many cases to supervise/preside over a specific synagogue. Other rabbis are simply private Torah-scholars.

Answer 3

They are experts in Jewish Law. The may have a variety of jobs including teaching, overseeing kosher food production, or providing spiritual leadership.

Answer 4

They give advice, advise people on Jewish law and are a representative of their community or congregation. They will also mostly lead a synagogue service.

Answer 5

The Rabbi is first and foremost a teacher, but has also come to be associated with the role of prayer leader.