About Booster Cables
People have been injured by battery explosions resulting from the use of jumper cables, but it's rare. Proper use of jumper cables should keep you safe. If you are concerned, booster cable manufacturers recommend wearing protective eyewear when working with booster cables.
Booster cables are basically two lengths of insulated copper cable that typically have a spring-loaded clamp on each end. For your convenience, most sets of jumper cables are joined together, separated from each other by insulation, but this separation is for convenience only. Individual cables will serve just as well.
Also, for your convenience, booster cables typically are differentiated as red and black, blue and yellow, or black and red. Often the manufacturer will stamp a "-"or "+" sign into the metal clips. This is also convenient. Remember that the cables are simply lengths of conductive material. The most important thing is, don't mix the power streams. If you hook the black cable to the positive diode on one car's battery, be sure to place the other end on the positive diode of the other car's battery. The same thing applies if you stick it to the negative diode. Most batteries are clearly marked. Pay attention, as batteries are inconsistent on placement.
When hooking up one terminal, be sure that none of the three remaining clamps touch each other. Depending on the condition of the insulator material surrounding the cable, you may choose to lightly clamp the unused ends to the insulation while manipulating either end. You may choose instead to separate them in your hand. In any case, separation is essential for proper booster cable use.
Booster cables work best on clean metal surfaces, so before connecting the cables be sure to remove the battery corrosion that is sometimes present. You can use a wire brush or toothbrush for this. Make this the first step.
Any time you work with electrical components, there are dangers to consider. But booster cables are simple and generally safe when used in the manner in which they are intended.