For Sabbath observing Jews, “work” is defined as a certain set of 39 (?) activities that are defined in the bible and relating to building the “Mishkan”. Generations of Talmudic rabbis then added new interpretations and requirements on these rules to adapt for new technology. eg, the prohibition against using electricity is because it relates to igniting a spark, which is one of the 39 prohibited activities (Or “malakha”)
Internet? No
Something breaks, fix it? No
Sit around all day? No :)
For many that keep the Sabbath, the time is spent eating, praying, and studying and there’s somewhat of a schedule. Friday night: synagogue, then big ceremonious dinner. Saturday morning: Synagogue. Saturday afternoon: big ceremonious lunch and study or sleep. Saturday evening: back to synagogue again. It’s a pretty full day.