Wikipedia has a definition. It is the subtractive manufacturing process of using baths of temperature-regulated etching chemicals to remove material to create an object with the desired shape. It is mostly used on metals... The process essentially involves bathing the cutting areas in a corrosive chemical .... Okay, enough of that! If you want to geek out some more, please feel free to learn everything you could possibly want to know by following the link above. But what you probably really care about is whether this is the right process for your client’s request.