Question

Silver is the best conductor of electricity but copper is used instead of silver for making wires. Why?

Answer 1

Silver is an expensive metal. Material needed for conductor should be cheap as wires are used extensively in almost every appliances. That is why silver can't be used to make wires
On a cost basis copper is nearly always used as it is relatively cheap and a decent conductor for most applications. Compared to copper silver has only slightly less resistivity however it has a higher density so on a resistivity to mass basis the two are roughly identical. Copper is also more malleable and ductile than silver and can be shaped easier and put under stress without damage. Twists and kinks in silver wire are more likely to result in cracks.