There are few devices in your life that you use more often and that offers more versatility than your smartphone. Encompassing so many devices in one, your smartphone works as a phone, calendar, computer, camera, eBook reader, video game console, music player and so much more. Smartphones also cost a lot of money, so it makes sense that you want to protect your investment.
This is also true regarding your other electronic devices and media. From hard drives to CDs filled with family photos and memories, you want to make sure that a storage case protects against a variety of hazards, such as water, dust, hard surfaces and more.
The most important thing you want to look for in a storage case is impact resistance. This is especially true for smartphones, which you are most liable to drop to the point of shattering the glass screen. Screens are particularly vulnerable to shattering if the point of impact is at a corner of the phone, so you should choose a case made of a shock-absorbent material that covers your phone's corners. Plastic cases are not ideal for impact resistance.
You should also look for a storage case for your electronics and media that is resistant to moisture. This is extremely useful if you need to transport important files on CDs or flash drives. Rain easily penetrates pockets, book bags and purses, and you don't want to lose an important work project because your storage method got wet.
Moisture resistance is also important in smartphone cases, especially if you use your smartphone during workouts. You don't want sweat to permeate your phone and cause damage. You can purchase cases that feature flaps that shield charging ports to keep sweat and moisture from short-circuiting your charging or headphone ports. If you work outside in the elements, a waterproof case is a must.
With electronics becoming increasingly portable, you expose them to greater risks, whether that is the weather or simple human clumsiness. It is important to utilize storage cases to preemptively protect your electronics and media.