Guide for the perplexed: DIY: do-it-yourself (fairly widely known) PEX: Cross-linked polyethylene, a form of polyethylene with cross-links. Increasingly pr

Guide for the perplexed: DIY: do-it-yourself (fairly widely known) PEX: Cross-linked polyethylene, a form of polyethylene with cross-links. Increasingly prevalent in plumbing applications. PCV: Polyvinyl chloride, a common plastic pipe, often white or black, may be rigid or flexible, widely used in plumbing for decades. "the world's third-most widely produced synthetic polymer of plastic (after polyethylene and polypropylene)" per Wikipedia. EMT: Electrical metallic tubing.