Some professional chefs are disdainful of cleavers, claiming they're coarse and unwieldy compared to a chef's knife. What they don't always realise is that cleavers come in different sizes and can be used for different jobs.
What is it? While a knife comes to a sharp point at the tip of the blade, a cleaver is more rectangular in shape.
How's it used? A chef's knife tends to be used in a rocking, back and forth motion, with part of the blade always on the cutting board. A cleaver is more often (but not always) used in a chopping motion, with the blade lifted completely from the cutting board.
What's it used for? Depending on the size and weight of the blade, a cleaver can cut through the smaller bones of sheep and cattle (if the user has the strength) or cut paper-thin slices of ginger (if the user has the skill). You can also use the flat side of the blade to crush garlic.
What to look for? Buy a cleaver that feels right: it should feel balanced, with neither the blade nor handle too heavy, and it should be the appropriate size for your hand and strength. A cleaver with a blade from 16cm to 18cm long will suit most people. With this, you can cut through chicken bones and chop vegetables. One with a thinner, smaller blade is better for finer cutting.
What else? Chinese cleavers are cheap: many cost less than $200. Expensive European brands include Sabatier and Wusthof. Cleavers are traditionally made of carbon steel, which is easy to sharpen with a steel or a whetstone. If you want to buy a European cleaver, look for those made of carbon stainless steel; pure stainless steel has to be sharpened professionally.