Orthodox Judaism is composed of many groups who share certain common beliefs and adhere to certain common structures in their religion. There is no organized, centrally led group that can be called "Orthodox Judaism", because the term, itself is very recent and is mostly used in American Judaic communities. There is actually no "Orthodox Judaism", but differences in the details and the adherence to observances in the Judaic faith.
The differences in the groups that are considered to be "Orthodox" are centered around differences in the details that are considered important in their observances and in their structures of belief. Some groups are liberal, others conservative. Some groups focus on the study of the Torah and on isolating from society to form their own communities. Others mix it up with everyone, yet still practice their faith in adherence to traditional structures.
The Torah, both written and spoken, as well as dedication to it, is the central point of agreement among Orthodox Jews.
"Normative Judaism" identifies the practices and beliefs of the Jews who were first organized as a nation at Mt. Sinai. Orthodox Jews adhere to the tenets of Normative Judaism that have been passed down with very little change through the generations since the origins at Mt. Sinai.
The first belief: That the Torah, written and spoken, originate from God and serve as the word of God, with the belief that God is not a construct of human belief, but a separate entity. The Torah is the written law as interpreted through the oral law.
The context: Orthodoxy encourages questioning. What is it that we are to do for God? We get our answers from the system of answering these questions that has been given to us.
The mystical origins: Orthodoxy adheres to the mystic beliefs formed during the Chasidic, Ashkenazi, and Sephardi movements in Judaism.
The Chasidic movements center in European movements, and include the Hasidim (also called Chasidic) and Mitnagdim.
The Ashkenazim lived, during the middle ages along the Rhine in parts of France and Western Germany, then spread to Poland and Lithuania. Ashkenazim now have settlements all over the world. The Ashkenazim focus on detailed Biblical and Talmudic studies.
The Sephardi are Jews who lived in Spain and Portugal, in some beliefs, as early as the time of King Solomon. The Sephardi left Spain and Portugal during the Inquisition and Expulsion of 1492. The "Sephardic Diaspora" led them to North Africa, Turkey and Greece. Also, during that time, the Marranos pretended to convert to Christianity, but practiced Judaism in secret. The Marranos were also expelled.