The vast majority of electrical wire is made of copper. Copper's electrical conductivity is very high, though silver's is higher. Silver's cost keeps it out of most electronics equipment; however, it does see use in some high-end, demanding applications.
Electrical conductivity is the measure of how well electric current flows through a material. It's measured in units of siemens per meter.
The conductivity of annealed copper is 59 x 10^6 siemens/meter. The resistance of a 24-gauge copper wire 1,000 feet long at room temperature will be about 26 ohms.
The conductivity of silver is about 7 percent higher than for copper, or 63 x 10^6 siemens/meter. A silver 24-gauge, 1,000-foot-long wire would measure about 24 ohms.
Because its conductivity is the second highest of any metal and its cost is low, copper sees use in most wire, connectors, printed circuit foils and related electrical parts.
Silver's higher conductivity and cost make it a niche product. It's used as wire and solder in specialty audio electronics.