In general, it is permissible to benefit from most electrical objects during Shabbat, provided they are preset before the start of Shabbat, and the status of the appliance is not manually modified during Shabbat. These include lights, heating, and air conditioning.

Main article: Cooking on Shabbat

Food may be kept hot when it is cooked before the start of Shabbat. There are various laws governing how this food is kept hot and served. Often, a blech or crock pot is used for this purpose.
[edit] Refrigerators

Though most Shabbat observant Jews permit opening and closing a refrigerator during Shabbat, some authorities require that the door only be opened when the refrigerator motor is already running. Otherwise, the motor will be caused to go on sooner by the increase in temperature indirectly caused by the flow of heat from the outside. Most refrigerators and freezers automatically set the motor to turn on and blow cold air whenever the thermometer registers a temperature that is too high to keep the food cold. However, Rabbi Shlomo Zalman Auerbach and most authorities permit opening the door because this result is indirect, and because there are additional grounds to be lenient.[16]

Additionally, any incandescent light which is triggered upon opening the door must be disconnected before Shabbat. It is not permitted to open the door if the light will turn on because, unlike with the motor running, the light turning on is a Biblical prohibition whereas the motor running may be a Rabbinic prohibition, and also, the light is turned on immediately as an effect of opening the refrigerator whereas the motor turning on is an indirect effect.[17]
[edit] Thermostats

Sparks
Intentionally creating sparks is prohibited as igniting a fire. Turning on some electrical appliances may generate sparks, but contemporary authorities do not consider this a reason to prohibit. The lighting of sparks is unintentional and might not occur, and the sparks are very small so they might not be considered final. With solid-state technology the probability of generating sparks is greatly reduced.

Some rabbinic authorities have questioned that if a thermostat for a heating or air conditioning system is set prior to the start of Shabbat, if changes made to the temperature of the room in which the thermostat is contained may impact the system's on/off status. Of particular concern is action that intentionally triggers the thermostat; for example, if the thermostat is set to turn on the room's heat, and an occupant of the room wishes the heater would turn on, opening a window to allow cold air into the room, thereby triggering the heat to turn on.

While most rabbis have ruled that the example of intentionally letting cold air into the room constitutes a violation of Shabbat, if the person opens the window for some other legitimate reason, and the cold air passage happens to be a side effect of his/her actions, no violation has occurred. Additionally, most agree that one who has no intention whatsoever as to the on/off status of the system, but his/her action impacts the status as an unintended affect, no violation has occurred.

A small number of rabbinical authorities have completely outlawed the use of heating/cooling systems controlled by a thermostat on Shabbat, declaring that human actions that trigger the system to turn on/off constitute a violation, regardless of intention.
[edit] Lighting

A lamp or appliance containing a light bulb may not be turned on or off during Shabbat. However, a timer can be set to turn a light on and off at fixed times. (See below regarding the "Shabbat clock.")

The Shabbat lamp is a special lamp in which the electricity remains on, but the light can be blocked out, thereby allowing the room that it is in to be dark or light at will. The lamp is constructed in such a manner that turning it "on" or "off" while powered on does not violate the laws of Shabbat. Specifically, the lamp operates by allowing the rotation of an outer shade that alternates between covering and uncovering a lamp that was pre-lit (before the onset of Shabbat) under the shade. Such concepts have existed in Talmudic literature, but have recently been commercialized by companies such as Kosher Lamp.
[edit] Television and radio

Most rabbinical authorities have prohibited watching television during Shabbat, even if the TV is turned on before the start of Shabbat, and its settings are not changed. However, most rabbis have permitted preprogramming a video cassette recorder or other similar appliances to record television programming during Shabbat for viewing thereafter.

Most authorities also prohibit turning on or listening to a radio. The reason is, although electrical current is not turned on, the radio makes a loud noise, falling under the Rabbinic prohibition of making a noise with an instrument designed to make noise. However, it may be permitted to turn up the volume of a radio that is already on because many authorities permit adding to an electrical current. Rabbi Eliezer Waldenberg prohibits changing the station on a radio using a dial, but Rabbi Auerbach permits this.[18]

Regardless of permissibility, all authorities feel that watching television, listening to a radio, or use of appliances for similar purposes on Shabbat violates the spirit of Shabbat and is not optimal.
[edit] Computers and similar appliances

While some authorities agree that the manipulation of a computer or any other appliance with a display screen (such as a digital watch or cellphone) is prohibited on Shabbos because of the use of electricity, other laws of Shabbat may also be broken when using a computer. One might be concerned that the acts of writing and erasing are performed, since one's actions on the keyboard or other control instrument impact what is displayed on the monitor. However, as Rav Gedalyah Rabinowitz pointed out in Halachah Urefu'ah (vol. V), words which appear on a computer screen are actually flickering many times a second. Therefore, the text on a computer screen can hardly be compared to written text. Text that appears on a computer console is not granted any permanence at all. In fact, words on a console cannot even be classified as semi-permanent writing, which may not be erased due to rabbinic decree (Shabbat 120b); it is not considered writing at all and one may even "erase" one of the Holy Names (of God) if it is displayed on the screen.

It is also questionable if the use of a keyboard, or other control instrument, to change what is displayed is a direct effect. Additionally, some of the action on the screen that occurs while the controls are manipulated are based on the preprogrammed behavior of the device rather than the person's actions. Even if the display was turned on prior to the start of Shabbat, and the on/off status of all lights remains the same throughout, other acts may constitute some violation. However, the use of a computer would be "Uvdin d'Chol" (weekday/mundane activities) which are prohibited rabbinically in order to preserve the spirit of sanctity of the sabbath by prevneting one form doing unrequired chores, gruling tasks and weekday-specific activities on the sabbath.
[edit] Clocks and watches

A clock may be used to view the time during Shabbat, since it is not touched or affected in any way by viewing it, and a watch may be worn during Shabbat. But an alarm clock should not be set before Shabbat, because one may forget upon awakening that it is Shabbat, and may turn it off. Some rabbis[who?] permit the use of an alarm clock if the shutoff switch is covered or some other object is put in place that would remind the user that it is Shabbat.[citation needed]
[edit] Telephones

Like other electrical appliances, telephones are bound by similar restrictions on Shabbat. Operating a telephone may involve separate prohibitions at each stage of the operation. Thus, removing a telephone from the receiver to produce a dial tone closes a circuit and makes a noise. Dialing closes more circuits and creates more noises. Speaking on the phone increases an existing current, but Rabbi Auerbach and many other authorities permit this. Hanging up the phone opens a circuit, which is a Biblical prohibition of "destroying" according to the Chazon Ish but a Rabbinic prohibition according to others.[19]

Dialing on many phones, including cell phones, also causes the numbers to be written on a display screen, thus violating the prohibition of writing (even though the writing is not permanent). If a phone call must be made on Shabbat, other factors being equal, it is preferable to use a phone without a display screen.

It is questionable if it is permissible to use an answering machine or voicemail to receive messages left during Shabbat, since one is benefitting from a violation of Shabbat, particularly if the caller is a Jew.[20]

In some cases, the telephone may be a lifeline in the event of an emergency, in which case, the laws of Shabbat are suspended, and a life-saving phone call may be made.

In Israel, a special phone has been invented for soldiers that allows phone calls to be made with minimal desecration to Shabbat for borderline situations in which it is not known whether a life-threatening emergency is taking place.
[edit] Microphones
Main article: Shabbat microphone

There are varying views on the use of a microphone during Shabbat. While most Orthodox rabbinic authorities prohibit the use of microphones, there has been some argument for allowing the use of a microphone in a synagogue that is turned on before the start of Shabbat on the basis that a microphone does not create a human voice, but rather amplifies it. Those in the majority, who forbid the microphone, have various concerns, including the conduction of electricity that is affected by the human voice, and the attention that is drawn from the sound coming from the speakers[21].

In recent years, a Shabbat microphone has been developed that broadcasts a constant sound signal, so the voice spoken into the device does not change the status of the electric current. But this innovation has not been approved by all Orthodox rabbinic authorities.
[edit] Laundry

Washing clothes is not permitted on Shabbat, whether by hand or machine. Most rabbinical authorities have prohibited allowing a washing machine or dryer to run on Shabbat, even if it is set before the start of Shabbat. If the machine is still running after Shabbat starts when this was not planned, no benefit may be derived from clothes or other objects in the appliance during that Shabbat.
[edit] Automobiles
Main article: Driving on Shabbat

While driving on Shabbat is prohibited directly because of sparks that are created by the ignition of fuel, modern automobiles also have numerous electrical components whose operation is prohibited during Shabbat. These include headlamps and other external and internal lights, turn signals, and gauges. Additionally, the operation of the vehicle involves many uses of electricity and electrical circuits.
[edit] Elevators
Main article: Shabbat elevator

Operating an elevator is generally prohibited for multiple reasons. However, Shabbat elevators have been designed automatically to travel from one floor to the next regardless of whether a human is riding the elevator or not, so many authorities permit the use of such elevators under certain circumstances.
[edit] Surveillance systems

The use of automated surveillance systems has been reviewed. Examples include closed-circuit television, video cameras, and motion detectors.[22] A passerby who walks within view of a surveillance camera may allow himself to be photographed for the benefit of the property owner, even though the photograph is not a benefit to the passerby, if he must pass by a surveillance camera to enter the building. This is called a pesik reisha delo nicha leih (Aramaic: פסיק רישא דלא ניחא ליה, loose translation: "an inevitable resultant action that does not benefit the one who indirectly caused that action").[23] However, it is prohibited to walk past a motion-sensitive light on Shabbat if the street is dark and because the turning on of the light substantively benefits the person, and it is a pesik reisha denicha leih (Aramaic: פסיק רישא דניחא ליה, loose translation: "an inevitable resultant action that does benefit the one who indirectly caused that action"). One is advised to avoid walking past the motion sensor or to close ones eyes when doing so if he or she knows that the motion sensor will activate a light switch.[24]
[edit] Static electricity

Most authorities permit separating clothes or performing other actions that might generate sparks due to static electricity.[25]

Abele Derer wrote:First of all, the Sabbath - the fact that all Jews keep the same Sabbath - serves as proof for the truths of Judaism. You skeptics claim that some later dude invented the Sabbath, and, istead of taking the credit for himself, claimed that God commanded millions of their ancestors on Mount Sinai that they must keep Sabbath. If your scenario is true, then the Jews would have rejected the Torah. They would have said, "How can you claim that millions of our ancestors, the entire nation, was commanded to keep the Sabbath, while we haven't heard of the damn thing from our ancestors." It is for this very reason that the Sabbath is given such prominence in the Torah, and it incurs the death penalty, because it serves as one of the strongest proofs for Judaism.

Second, this whole blog is shockingly stupid. Your basically claiming that "since we can't understand why God would care if we light a match, it therefore must be that God did not command us not to light a match." Does that sound logical to you? If so read it again.