There are three types of digital camera: compact, bridge et reflex.
The compact housing has a small size. Also "ultra-compact" models exist, their design is often more successful, but they are generally less efficient.
The bridge is distinguished by the compact zoom powerful, but cumbersome, integrated housing.
The reflex has two distinct components: the camera and lens. It is possible to adapt to multiple objectives housings depending on the subject or shooting distance. This modularity improves the photography.
Before any purchase, ask yourself a fundamental question: What will you do with the camera?
Holiday, memories, family
The criteria for handling, portability and ergonomics are essential fluid. The compact, small, is ideal for tourism, in a crowd. You can easily get out of its case and then put it away. Minimum settings required for this type of device you will not miss anything from your holiday (beginner). Limited in the number pixels a few years ago, the compacts are now highly competitive.
Semi-nomadic trips, family celebrations The bridge, a little larger, with a record of better quality, suitable for family celebrations (marriage, baptism) and one-day getaways. Think that over several days, an even lighter, eventually becomes cumbersome. It is quite easy to use (intermediate level)
"Sedentary" Photography dedicated composition The motivation is that of a most esthetic or artistic work (landscapes, moving subjects). The reflex is best suited to those conditions of shots. Its use is limited in time because of its lack of maneuverability. A higher degree of control functionality of the device is required (expert level).
Expansion and printing / viewing screen? If you plan to watch your pictures on a computer screen, the compact and bridge made are the models you need. Prefer the bridge occasionally if you print your photos. If you have a care in the print quality, a reflex is good: improved depth of field, lack of grain, expansion opportunities without pixellisation.
The technical criteria
Number of pixels. Criterion often viewed as decisive. It is less and less thanks to advances in cameras in this area. Important when printing an enlarged photo or a detail.
Screen and the viewfinder. The LCD screen has replaced the optical viewfinder on compact cameras. In bright sunshine, it is difficult to be proud to frame your photos (unreadable). If the framing seems important, prefer a "bridge". It has a mini screen more readable if the sun (but less accurate).
Aim. It must have a zoom sufficient to allow successful shooting in any situation. For large frames (pictures of people, landscapes), be attentive to the presence of a wide angle or a super-angle lens.
Stabilizer. It corrects the quake photos for a reported net. Present on a majority of devices.
Image storage. 4 types of cards exist. Check compatibility with your device. Storage capacities greater or lesser extent. For shooting burst, check the write speed of the card.
Speed. Time as the camera takes to power and to take the picture from the moment you press the shutter.
Assistance shooting. The device calculates just about the type of photography (portrait, landscape) and adjust the focus and exposure.
The colors, the sensitivity of the device to light (for the operation of the auto-focus), the power of Flash are important parameters. These features are generally provided on the evaluation sheet for the device. It is difficult to obtain optimal performance for each parameter. Choose according to his priorities for the use.
Computer and peripheral
Check the capacity of your computer hard drive (storage) for your photos. Even a simple graphic card will display photos and video. For retouching, some very heavy software like Photoshop, requires a good amount memory, at least 512 MB