Unfortunately because genuine image stabilisation systems offer such a big advantage, but go by so many different names, many manufacturers have added features to their cameras which may at first sound like image stabilisation, but are in fact nothing of the sort. Names such as "anti-shake", "digital image stabilisation", "shake reduction" and others all sound like they do the same job as the systems described on the previous page, but in fact many of them offer no real image stabilisation at all. They are all just different names for the same thing; increased ISO sensitivity.
The ISO setting on a digital camera is a means of adjusting the gain of the sensor, and increasing the ISO boosts the signal output from the individual photocells, but like any form of signal amplification it also increases the level of noise in the signal. Although some manufacturers' sensors perform better at high ISO settings than others (Fujifilm's SuperCCD and Sony's Super HAD systems are particularly good) all digital cameras suffer from increased image noise at high ISO settings. Increasing the ISO setting means that the camera's metering system can set a faster shutter speed for a given light level, which can reduce the effects of camera shake in low-light situations, and can also reduce the blurring caused by a moving subject, but the increase in image noise often drastically reduces the overall image quality, and can cause inaccurate colour reproduction. Since these high-sensitivity anti-shake systems are usually found on cheaper cameras with the smaller 1/2.5-inch sensors, and with less sophisticated noise reduction systems, they almost invariably result in very poor image quality, and their use should be avoided unless there really is no alternative.
When you are buying a new camera you should pay special attention to any claimed "anti-shake" system. Optical and moving-sensor systems are vastly superior, and manufacturers will usually draw attention to them as real and valuable features, so if the claimed system is not specifically described as one of these two, then it is very likely that it is simply a high-ISO feature. This is another good reason to read reviews of a new camera before making your purchase, since any good reviewer will draw a distinction between these different systems. Do your homework, and don't be deceived into buying something that isn't what it appears to be.