Solder is typically an alloy of lead (Pb) and tin (Sn). Traditional solder, widely used for joining metals in plumbing and electronics, is an alloy primarily composed of lead and tin. The ratio of lead to tin affects the melting point and properties of the solder. Common compositions include 60% tin and 40% lead, or the eutectic alloy of 63% tin and 37% lead which has the lowest melting point. Due to environmental concerns about lead toxicity, lead-free solders have become increasingly popular, especially in electronics. Lead-free solders often consist mainly of tin alloyed with other metals like silver (Ag), copper (Cu), and sometimes bismuth (Bi) or antimony (Sb). However, without specifying “lead-free”, the standard Pb-Sn alloy is implied.