There is a mitzvah to recite Shema in the morning and at night. The commentaries explain that this declaration of accepting Hashem as our King is appropriate both by day, which is symbolically representative of good times, as well as at night, which is symbolically representative of difficult times, when we cannot clearly discern Hashem’s plan. Alternatively, the day Shema is the acceptance of Hashem as King even when we are rushing into the workday, while the night Shema represents acceptance of His rule even when we are involved in quiet or leisure time.
In addition to reciting Shema in the morning and at night, it is common practice to recite Shema (at least the first paragraph) when we go to sleep. Click here for the Take Ten for Talmud class Brachos 4- The Bedtime Shema
Shema is comprised of three sections taken from Torah (Shema-Vahavta, Vohoyo Im Shomoah, and Tzitzis) with one added phrase (Boruch Sheim Kivod Malchuso Liolam Voed) added for a specific reason. Here are some Take Ten for Talmud selections that will guide you through the Tlmud passages on the topic.
The final paragraph of Shema (Tziztis) is very significant, and was included in the recital of Shema, for a number of reasons.
In the previous paragraph of Shema we described the importance of observing mitzvos. Tzitzis is a mitzvah which reminds us
of the other mitzvos. It is like the uniform of the Jew, reminding us of our mission. (See the section on Tzitzis for more about this.)
Additionally, the paragraph of Tzitzis concludes with a statement about Yetzias Mitzrayim/ The Exodus from Egypt. This is very
significant because we are obligated not only to commemorate the Exodus on Pesach, but to remember the Exodus every day of our lives.
By incorporating the paragraph of Tzitzis into the Shema we are guaranteed to remember the Exodus every day of our lives.