All of us had the experience of shooting photos just to find out they look blurry or too soft. In almost all cases the reason for that is camera movement. When the camera moves while the shutter is open the result is a soft or blurry photo. Usually camera movements are small and for that reason in high shutter speeds the camera does not have an opportunity to move enough. However in some scenarios such as slow shutter speeds or high zoom values even the tiniest movement will result in a blurry photo.
Most photos are taken when the camera is held in your hand. The hand is an unstable platform and tends to move quite a bit. Moreover new digital cameras are smaller and lighter than ever before and are much harder to keep stable. Another cause for camera movement is aggressively pushing the shutter button which in return moves the camera. It is always better to squeeze the shutter button very slowly to prevent the camera from moving. Choosing the right camera for weight, grip and shutter button sensitivity is a recommended way to minimize camera movements in the future.
As a general rule photos that are taken with slow shutter speeds or high zoom values should be taken using a more stable platform than your hand. A stable platform can be anything that is stable: a table, a shelf, a chair or a newsstand in the street. However the platform that is considered the most stable and professional is the tripod.
There are many types of tripods and they vary in size, weight, price and other features. The most important criteria when choosing a tripod is to pick one that will be easy to use. For example if you are traveling consider a tripod that is easy to carry and lightweight otherwise you will end up leaving the tripod in the hotel room while missing great photo opportunities. On the other hand if you take photos in a studio consider a heavier professional tripod.
Another important feature to consider is the tripod's height. Many tripods can be locked at any height up to a maximum. Ideally you would want a tripod that extends to your height allowing photos to be taken from the same angle as your eyes as if they were taken by hand. Many portable tripods extend to a waist height or less. In these situations the tripod will be put on a raised platform or the photos can be taken from a low angle.
In cases where a tripod is not available but a stable platform is needed you can improvise by using many other available platforms around you. For example you can place the camera on a table when taking a photo or if you're outdoors you can use a newsstand, a tree to lean on, a fence or anything else that is stable enough.