If you melt chocolate and let it cool, it will set as an unattractive, dull brown mass streaked with grey: its texture when eaten will be chalky and grainy. Tempered chocolate, on the other hand, is shiny, even-coloured, crisp, smooth tasting..... in short much, much better.
The reason for the difference is complicated, and in order to understand it completely one would need to study the behaviour of the chocolate crystals at the molecular level. For our purposes it is sufficient to say that in tempered chocolate the chocolate crystals have formed in a completely uniform way.

The trick to tempering is to control the temperature of the melted chocolate very precisely: first cooling it and then reheating slightly. At each step of the way the temperature of the chocolate must be precise and uniform: even tiny variations can ruin the result. It is also very important to mix the chocolate in just the right way: too little mixing will prevent the right crystals from forming; too much mixing will cause the fat in the chocolate to separate from the cocoa solids.

The Chocolatier électronique computer-controlled chocolate temperer takes all the risk and difficulty out of the process. The Chocolatier électronique contains both a super-sensitive thermometer and a mini-computer which do the job for you. Not only will the machine produce perfectly tempered chocolate every time, it will also keep the chocolate in temper for hours on end, if necessary.

The original Chocolatier électronique is perfect for most uses, tempering as little as 100gm and up to 3kg/hour or more when fed with melted chocolate from a bain-marie. The Chocolatier électronique is fast too, melting 700gm of chocolate and bringing it into temper in about 20 minutes, all at the touch of a button. If you plan to work with more than one colour of chocolate at the same time, additional bowls and thermometer/baffles are available so you can change colours quickly.

Recommended chocolate making tool by ChocoPal.com: Chocolatier électronique