A rabbi is simply a teacher, a person sufficiently educated in halakhah (Jewish law) and tradition to instruct the community and to answer questions and resolve disputes regarding halakhah. Unlike the Christian priest, he has no more authority to perform rituals than any other adult male member of the Jewish community. When a person has completed the necessary course of study, he is given a written document known as a semikhah, which confirms his authority to make such decisions. Rabbis get married as any Jewish man.
In Judaism, religious services and prayers are not necessarily led by rabbis, although organised communities need a spiritual leader.
Synagogue, the Jewish house of prayer
At a minimum, a synagogue is a beit tefilah, a house of prayer. It is the place where Jews come together for community prayer services. Jews can satisfy the obligations of daily prayer by praying anywhere; however, there are certain prayers that can only be said in the presence of a minyan (a quorum of 10 adult men), and tradition teaches that there is more merit to praying with a group than there is in praying alone. The sanctity of the synagogue for this purpose is second only to The Temple.
A synagogue is usually also a beit midrash, a house of study. Contrary to popular belief, Jewish education does not end at the age of bar mitzvah. For the observant Jew, the study of sacred texts is a life-long task. Thus, a synagogue normally has a well-stocked library of sacred Jewish texts for members of the community to study. It is also the place where children receive their basic religious education.
Most synagogues also have a social hall for religious and non-religious activities. The synagogue often functions as a sort of town hall where matters of importance to the community can be discussed.
In addition, the synagogue functions as a social welfare agency, collecting and dispensing money and other items for the aid of the poor and needy within the community.
Can a non-Jew visit a synagogue?
Non-Jews are welcome to attend services in a synagogue, whether they come out of genuine curiosity or to join a friend in celebration of a Jewish event. When going to a synagogue, one should dress as one would for church or mosque: formally and modestly. A man should wear a skullcap (kippa); kippas are available at the entrance for those who do not have one. In some synagogues, married women should also wear a head covering. Non-Jews should not, however, wear a tallit (prayer shawl) or tefillin. Men and women are seated separately in an Orthodox synagogue.