Egypt's electrical supply runs at 220–230V, 50Hz, using the European-style round two-pin plug (Type C and F). Travelers from the UK, EU, and most of Asia and Australia generally only need a simple plug adapter, since their home voltage is already compatible.
What North American travelers need
Travelers from North America, where the standard is 120V, may need both a plug adapter and a voltage converter for devices that aren't dual-voltage — though most modern phone, camera, and laptop chargers are dual-voltage by default (check the fine print on the charger itself), in which case only the plug shape needs adapting.
It's worth packing a universal adapter before you travel rather than assuming one will be easy to find locally — hotels and cruise ships sometimes have a few available at reception, but it's not something to count on for your whole trip.
See What Should You Pack for a Nile Cruise? for the rest of the packing list beyond electronics.