Speaking of power. That is also an important factor to consider. Most cameras operate on AA batteries. This allows the greatest flexibility in powering your camera. If you find your batteries depleted and no time to charge them, you can always use single-use alkaline batteries that can be purchased almost anywhere.
Some cameras use proprietary batteries packs.
The benefit to these proprietary battery packs is that the cameras usually can act as a charger. On the negative side, when you run short of battery power you can't pop in some AAs from Wal-Mart and keep shooting. Most digital cameras will include a flash unit. Flash units usually have several operating modes. These will include always on, off, red eye reduction, and others.