Israel and Turkey’s electrical systems are different from the United States in two ways: (1) the voltage of the current and (2) the shape or configuration of the plug.
The United States uses 110 volts but Israel and Turkey use 220 volts. Many modern electrical devices and appliances (electric razors, tablet computers, phone chargers, camera battery chargers) are equipped for 110v-240v. It will say so on the device itself or on the device’s charger in very tiny print. Check your equipment before you travel!
If you plug into a 220v outlet a device rated only for 110v, it will fry your device. This can be quite costly and will likely cause unwelcome distress. If you have devices that run only on 110v, then you will need to bring an electrical transformer/convertor that works in Europe. (If you plan to bring appliances that get very hot, such as curling irons or hair dryers or coffee machines, then you will need a transformer that can handle the correct wattage.) Here is an example of one:
Electrical plugs in the United States have two flat prongs (sometimes accompanied by a third round prong for grounding), but all of the outlets in Israel and Turkey have round holes. Your plugs will not fit, no matter how hard you try to force them.
For those using a transformer/convertor, chances are it will come with an adapter already built-in (like in the photo above). For those who do not need a transformer/convertor (i.e. if all of your devices can handle 220v), then you will just need electrical adapters to change the shape of your plug. Israel uses round pins, the same as in Europe (type C). Take note whether your devices’s plugs are three-prong or two-prong to make sure the adapter will receive them. Adapters should not cost very much.
Finally, if you plan to travel with lots of devices that require electricity (e.g. battery chargers, laptop, smart phone), then consider how many outlets you will require. If you need many outlets, then you may want to bring a multi-plug outlet. There are now outlets available that combine adapter and multi-plug, plus they come with USB ports so you can charge directly from the outlet.