研磨是一种将固体物质化为较小颗粒的单元操作。为了研磨不同物质，人类会使用各种研磨器，包括手动的臼、由动物、风力或水力推动的磨坊、以及由电力驱动的电磨等。

在研磨作用下，机械力克服了固体物质内部的链合力。被研磨物质的尺寸、形状皆有改变。

研磨也是一种精加工方法。利用涂敷或压嵌在研具上的磨料颗粒，通过研具与工件在一定压力下的相对运动对加工表面进行的精整加工。或者，将磨料颗粒与添加剂混合分散于溶剂中，通过与加工表面的相对运动进行加工以达到更高的光洁度。

A mill is a device that breaks solid materials into smaller pieces by grinding, crushing, or cutting. Such comminution is an important unit operation in many processes. There are many different types of mills and many types of materials processed in them. Historically mills were powered by hand (e.g., via a hand crank), working animal (e.g., horse mill), wind (windmill) or water (watermill). Today they are usually powered by electricity.