This is not a book for beginners. If you want an introduction to Jewish prayer, see “Entering Jewish Prayer” (Reuven Hammer) or “To Pray As a Jew” (Hayim Halevy Donin).
This book is the most thorough academic study of the Jewish liturgy ever written. Originally published in German in 1913, and subsequently updated in a number of Hebrew editions, the latest edition now has been translated into English by Prof. Raymond P. Scheindlin. It covers the entire range of Jewish liturgical development, beginning with the early cornerstones of the siddur; through the evolution of the medieval piyyut tradition; to modern prayerbook reform in Germany and the United States.
The only problem is that it doesn’t deal with the liturgy of Conservative Judaism, except in a few minor references. To learn more about that liturgy consult the introduction to “Siddur Sim Shalom”, ed. Jules Harlow, and the introduction to “Siddur Sim Shalom for Shabbat and Festivals”, ed. Leonard Cahan, and the section on liturgy in the Encyclopedia Judaica.
The publisher writes: Fifteen years in the making, The Encyclopedia of Jewish Prayer is a monumental achievement. Never before has such a comprehensive resource been available to those searching for answers to questions on Jewish prayer. Macy Nulman has provided, in one unique, accessible volume, information on each and every prayer recited in the Ashkenazic and Sephardic traditions, creating an invaluable tool for study or quick reference. Arranged alphabetically by prayer, the encyclopedia entries include extensive liturgical information on the prayers, their composers and development, the laws and customs surrounding them, and their place in the service. All prayers, including not only prayers recited in the synagogue, but also the Grace After Meals and the prayers to be said before going to bed, prayers for special occasions such as weddings and circumcisions, prayers for the funeral ritual and for private devotion, are featured. The entries make extensive use of cross-referencing and bibliographical information to facilitate further study. In addition, the author discusses the many poetic insertions, known as piyyutim, recited on special Sabbaths, Holy Days, and festivals… it contains several indexes: two title indexes – one in Hebrew and one in transliteration – as well as an index of biblical verses and a name index.