Bright sun can cause harsh light on faces, with deep shadows around the eyes or under hat brims. This shows up even stronger in the resulting photographs.
There is a solution, something that you can do immediately whenever you are faced with harsh shadows on a nearby subject. (Flash wont reach far off subjects, unless it is very strong, which most of the basic ones aren't)
Nearly all digital cameras allow you to force the flash to fire in these conditions to fill in those harsh shadows. Some cameras have a “fill flash” setting of some sort, too, but all you really need to do is turn the flash on and use the “always on” setting.
The camera then adds flash to the dark shadows, opening them up and revealing your subject much better.
This works only for subjects that you are fairly close to, though the actual distance is affected by the power of the in-camera flash. Usually, fill flash works best at distances of about 8–9 feet.
Pros often use accessory flash for added power to boost this distance. Fill flash limits the shutter speed and f-stop possible with digital SLRs. You cant shoot at higher shutter speeds along with the flash as it wont synchronise with the shutter. The trick lies in kind of balancing the available ambient light with the flash so that the use of flash is not obvious in the photographs.
For more in depth information on flash photography, check out one of the online photography courses by Munish Khanna