A Kettlebell was originally a cast iron weight that looks like a cannonball that has a handle across the top. In Russian it is called a Girya and the main piece of equipment used in the sport of Girevoy. They were developed in the 1700s to weigh crops. Farmers became stronger and used them to show off their physical prowess at festivals. They’ve been used in competition throughout Europe since the 1940s and came to the US in the 1960s.
Today, Kettlebells are weights that are often covered in softer vinyl material and colored. They are inexpensive and can be easily purchased for a home gym. The current balls vary in weight from 4 pounds to 175 pounds. However, because the weight is shaped differently, and you leverage your body differently, it will exert more force on your body that the 4 pounds to 175 pounds.
The weight is also a bit more awkward than a standard hand weight. Because of the way the weight is used, you hold it out farther from your body making it tougher to balance. This increases your strength, balance and coordination with the equipment.
Because they handle so differently from traditional hand weights, you can injure your shoulders, wrist and lower back if you don’t use the equipment properly.  It’s important to use the lightest weight possible while you are learning to use the equipment to reduce your risk of injury. If possible, you should also have a fitness trainer walk you through using the equipment the first time.
As for any other exercise using weights, you want to be sure your body is planted firmly on your heels for a strong foundation against which you’ll improve your strength. Also, you should never hold the kettlebell directly over your head because it is not as easy to grip as traditional weights. It would be catastrophic to have a kettlebell slip from your hands and land on your head.
Using a kettlebell is like using any other weight. You should protect your joints and especially your lower back. Don’t slouch your shoulders or round your back. This only increases the weight load on your lower back.
Kettlebells are important to develop explosive action and motion and will also help you increase your strength. However, if power and strength is all  you are after, then traditional weights will are more than adequate for the job. Kettlebells are  one the trendiest items at the gym, but not always necessary for your particular needs.
Traditional weights are used slowly with higher weight and lower reps (muscle build) or lower weight and higher reps (fat burn). But, kettlebells are used for higher and faster repetitions to activate more muscle groups. The intent is to increase the muscles’ ability to perform fast and powerful movements repeatedly. Using the kettlebell can help improve your ability to accurately swing your golf clubs after 16 holes or block a basketball shot late in the game.