The electrical current in Israel is 220 volts, 50 cycles alternating current (AC); wall outlets generally have three round holes, but most of these will also take continental-type plugs with two round prongs. Some outlets require plugs with three flat prongs in a Y shape.
If your appliances are dual-voltage, you need only a small adapter plug. Most large hotels provide 110-volt outlets marked for shavers, but don’t use those outlets for high-wattage appliances such as blow-dryers. Most laptops operate equally well on 110 and 220 volts and so require only an adapter.