A wire is very fascinating material to work. It can be purchased in different sizes. The size is called the gauge of wire, but some European suppliers measure it in mm. The larger the gauge number the smaller will be the diameter of. In general wire is a round metal string, but you can find also wire that is half round or squire. The hardness of wire depends from what kind of metal it is made. Gold, silver, copper and aluminum are soft metals and wires from these materials are easy to bend. Stainless steel and brass wires are harder and jewelry made from these materials will be more durable. The best way to find out the best wire for a particular project is practice, and, I advise, keep scraps and failed projects. These pieces are great for practice! I love to use craft wire, it comes in wide variety of colors and it cheaper as precious metal wires. I like to keep material costs low to have affordable jewelry for everyone.