Siddur is the prayer book used by Jews around the world. The word Siddur, in Hebrew, means “order”, and shares its root with the “Seder” which we do on Passover (also order). There are various customs that have developed in the long exile since Jews have been spread throughout the world, but they all share major commonalities. Some of the most common customs include the Ashkenazi, of Jews mostly from Germany and parts of Europe, Sefard, which is typically a Hasidic custom also from Europe with Kabbalistic elements. Sephardi is generally Jews from the middle east and north Africa, which contains a number of specific customs for Iraq and Morocco, just to name a few.
The siddur, as the name implies, contains the order of prayers that are said throughout the day. It starts with the morning blessings that are said upon rising and moves into the Sharcharit morning prayer. After, follows Mincha, the afternoon prayer, and then comes the evening prayer, Arvit or Maariv. Everything essential to the Jewish calendar and Jewish life is added after this, including blessings after meals, pubic torah readings, additions for Shabbat, holidays and fast days, etc. Each publishing company adds its own style, emphasis, and additions. Some contain additional commentary to help the user to understand and appreciate the text. A number of companies translate the text into the native language of the user, alternating pages.
The siddur has had a very interesting history, because like other ancient books, until the revolution of the printing press, many books were out of reach of the common man, either because of price, or lack of literacy. Before this time nearly all prayers were memorized, and if not, then the prayer service was altered in some way to allow those who did not know it to still participate.
At the end of the second temple period, the Men of the Great Assembly, instituted the central part of prayer called “Shemoneh Esreh” known for its 18 blessings. This was the starting point of Judaism as it is known today as organized central prayers helped to maintain a common bond between the Jewish people in the world. From this time onward there has been some “order” of prayers for everyday life.
A Siddur like all Hebrew text are read from right to left. This means if it is translated with a foreign language on one page and Hebrew on the other, then the pages will turn opposite then what one is used to for one of the languages. Some even contain interlinear which have the exact translation under the Hebrew word. Prayer is a private matter, so although it is ideal to pray in Hebrew, and share this characteristic with the majority of the Jewish people, it can and should be read in your native language if you do not understand Hebrew. The commentaries included in many siddurim are a great way to allow for better understanding.