The week refers to the creation of the world. H" has created the world in six days and the seventh He rested from His work.
He has sanctified the seventh day, the Shabbat (rest).
During the week there are three daily prayers: in the morning after daybreak, in the afternoon and in the evening after nightfall.
The days of the week do not have names: they are numbered instead.
The first day is Sunday, the last is Shabbat.
The day in the Jewish calendar starts from the previous evening at nightfall.
For instance, the Sabbath begins on Friday evening.
The ritual time is not marked by the watch, but by sunrise and sunset.
This is the instant when the night settles, which makes the date change.
The time of commencement of the days is not fixed, because the night does not fall at the same time throughout the year and at different points of the globe.
This leads in particular to the fact that the time of entry of Shabbat varies from one week to another and from one place to another.
The sunrise and sunset depend on the date and location.
The schedules of Shabbat and prayers are calculated for the city that you can set here.