Communal prayer is an important feature of Judaism. Though prayers can be said anywhere, according to halakha Jews should ideally pray three times a day in a minyan, and a synagogue's primary purpose is typically to accommodate such communal prayer.
Synagogues are not used only for prayer, but also for communal activities, adult education and Hebrew schools for school-age children, hence the common Yiddish term shul for synagogue, which comes from the Middle High German word for school. Portuguese Jews call it esnoga, which derives from "synagogue".
Typically a synagogue (especially in North America and in Europe) will have a dual leadership: a lay leadership comprising a committee and a president (or chairperson) who are democratically elected by all members, and a spiritual guide, a rabbi, appointed by the lay leadership. A rabbi is not essential and indeed many synagogues do not have one.
Most Conservative and many Orthodox Jews refer to their houses of worship as synagogues; many Orthodox Jews use the Yiddish term shul (meaning "school"), and a few use the Hebrew term Beit Knesset (meaning "house of assembly"), or, amongst some Sephardim, the Spanish and Portuguese term esnoga. Most Reform and some Conservative Jews use the term "Temple" to describe their house of worship, but most traditional Jews find this term inaccurate, as Judaism has historically only had one Temple, the Temple in Jerusalem.
Most Conservative and Orthodox synagogues have prayer services every day; a morning service, and a combined afternoon-evening service. Larger (particularly Orthodox) synagogues may have multiple morning, afternoon, and evening services at different times, to accommodate the schedules of their congregants. There are special services on Shabbat (the Sabbath) and on the Jewish holidays; again, larger (particularly Orthodox) synagogues may have multiple simultaneous or overlapping services in different rooms, geared to different groups (e.g. early risers, families, children, young adults). Many Reform Temples only have prayer services once or twice a week.
Many Jews have a regular place of worship that is not a synagogue by the usual definition of the term. Many Haredi Jews worship in shteibels (Yiddish: "little booths"), rooms in private houses or places of business set aside for the express purpose of prayer. Shteibels do not offer the communal services of a synagogue, and are for prayer services alone. Many non-Orthodox Jews have formed chavurot (prayer fellowships) which meet at a regular place and time, usually in someone's house or apartment
* Blueprint for synagogues
It is a myth that synagogues are based on the destroyed Temple in Jerusalem. There is no set blueprint for synagogues and the architectural shapes and interior designs of synagogues vary greatly. The influence of other local religious buildings can occasionally be seen. The myth may have arisen because synagogues have been referred to in the Rabbinical Literature as Small Temples and indeed their popularity originated with the destruction of the original Temple as an alternative to the central worship in Jerusalem. According to tradition, the Divine Presence can be found when there is a minyan (a quorum, of ten — in Orthodox Judaism defined as ten Jewish men age 13 or over).
A synagogue may contain any (or none) of these features: an ark, called aron ha-kodesh by Ashkenazim and hekhal by Sephardim, where the Torah scrolls are kept (the ark is often closed with an ornate curtain (parokhet) outside or inside the ark doors); a large elevated reader's platform, called bimah by Ashkenazim and tebah by Sephardim, where the Torah is read (and the services conducted from in Sephardi synagogues); a ner tamid, a constantly lit light as a reminder of the constantly lit menorah of the Temple in Jerusalem; mainly in Ashkenazi synagogues, a pulpit facing the congregation to preach from and a pulpit facing the Ark for the Hazzan (reader) to lead the prayers from. A synagogue may have artworks — especially ornamentation of the main interior features; but normally not 3-dimensional artwork (sculpture) depicting naturally occurring objects, as these are considered to be like idolatry.
* Famous synagogues
Lesko synagogue, PolandOld New Synagogue in Prague, Czech Republic, is the oldest synagogue in Europe dating from the 11th century. (1574 synagogues were damaged or destroyed on Kristallnacht by Nazis in Germany and Austria, including many of the greatest synagogues of Europe.)
Touro Synagogue in Newport, Rhode Island, USA is the oldest synagogoue in North America, it was dedicated in 1763.
The synagogue in the old city of Kochin, Kerala State, India, is from 1568.
In Israel there are many archaeological ruins of synagogues from thousands of years ago, but the small ruined synagogue at Masada is believed to be the world's oldest, and the only one known to date from the time of the Second Temple.
Great Synagogue of PlzenThe largest synagogue in the world is Temple Emanu-El on Fifth Avenue, New York City, USA with an area of 3,523 sq m. Other large synagogues are the Great Synagogues on King George Street, Jerusalem, Israel; Dohány Street Synagogue, Budapest, Hungary; and the Great Synagogue in Plzen, Czech Republic.