A synagogue is a Jewish house of prayer. Synagogues usually have a large hall for prayer (the main sanctuary), smaller rooms for study and sometimes a social hall and offices. Some have a separate room for Torah study, called the Beit midrash. Synagogues are not consecrated spaces, nor is a synagogue necessary for collective worship. Jewish worship can be carried out wherever ten Jews (a minyan) assemble. A synagogue is not in the strictest sense a temple.
There is no set blueprint for synagogues and the architectural shapes as well as interior designs of synagogues vary greatly. In fact, the influence of other local religious buildings can often be seen.
Synagogue Wikipedia Entry