銲料，通常为锡的合金，故又称銲锡，为低熔点合金，在銲接的过程中被用来接合金属零件， 熔点需低于被焊物的熔点。

一般所称的焊料为软焊料，熔点在摄氏90~450度之间 ，软焊广泛运用于连接电子零件与电路板、水管配线工程、钣金焊接等。手焊则经常使用烙铁。使用熔点高于摄氏450度的焊料之焊接则称为硬焊（hard soldering）、银焊（silver soldering）、或铜焊（copper brazing）。

一定成分比例组成的共晶合金具有固定熔点，而非共晶合金拥有分别的固相温度及液相温度，当銲料处在固相温度及液相温度之间时，会呈现固态粒子散布在液态金属的膏状。焊接电子电路时，若焊料仍未完全融化就移除热源，会造成不良的电路链接，称之为冷焊点(cold solder joint)，共熔合金没有固液共存的温度范围，较能防止上述问题。不过，拭接铅管的接头（wiped joint）反而是趁焊料冷却至固液混合的膏状时，涂抹平整并确保无缝不漏水。

Solder (/ˈsoʊldə/, /ˈsɒldə/ or in North America /ˈsɑːdər/) is a fusible metal alloy used to create a permanent bond between metal workpieces. The word solder comes from the Middle English word soudur, via Old French solduree and soulder, from the Latin solidare, meaning "to make solid". In fact, solder must be melted in order to adhere to and connect the pieces together, so a suitable alloy for use as solder will have a lower melting point than the pieces it is intended to join. Whenever possible, the solder should also be resistant to oxidative and corrosive effects that would degrade the joint over time. Solders intended for use in making electrical connections between electronic components also usually have favorable electrical characteristics.