For six days we work, eat, sleep, exercise, and pray. Then, on the seventh, we pause to reconnect with God. Now prayer isn't just another item on the list; it defines the day. Without the pressures and distractions of work, we become more contemplative and focused—precisely the state that prayer requires.
At nightfall, Kabbalat Shabbat, the Welcoming of Shabbat, takes place. The service consists of a series of six psalms, representing the six days of the week, followed by a mystical hymn welcoming Shabbat (Lecha Dodi).
Then comes the typical evening service, adapted to the spirit of the day, followed by another psalm and ending with the Aleinu hymn, like the rest of the prayers.
In the central prayer, the Amidah, instead of including the same petitions to God that we say during the week, which would interrupt the atmosphere of Shabbat, a blessing is said that speaks about the specialness of the day.