Different types of plumbing pipes include:
Copper pipe - Used for decades as the most common water supply pipe. Copper pipe and tubing comes in a variety of sizes and types.
Type L - Thick walled hard/soft copper
Type M - Thin walled hard/soft copper
Type K - Thick walled hard/soft copper
Steel pipes are another type of metal piping that come in a variety of different styles. Standard steel pipes are circular welded non-alloy pipes that have a cross-section with an outside diameter that is no more than 16 inches. The surface of a standard steel pipe is typically painted, galvanized or black with the end finished either plain, beveled, threaded or thread and coupled. Standard steel pipes are designed for low pressure transportation of natural gas, water and other liquids and gas. They can also be used for light load-bearing applications such as shipbuilding and trucking.
PVC/CPVC - Used as a cold water supply pipe in many countries around the world because of the price but lacks long term durability.
PEX - Is cross-linked polyethylene tubing and has become the standard in new building construction. PEX comes in a variety of colors and is used for plumbing and heating purposes.
Galvanized pipe - May still be found in many homes but is seldom used anymore because of water discoloration, cost and difficult repairs.
A fitting is used in pipe and plumbing systems to connect straight pipe or tubing sections, to adapt to different sizes or shapes, and for other purposes, such as regulating or measuring fluid flow. The term plumbing is generally used to describe conveyance of water, gas, or liquid waste in ordinary domestic or commercial environments, whereas piping is often used to describe high-performance (e.g. high pressure, high flow, high temperature, hazardous materials) conveyance of fluids in specialized applications. The term tubing is sometimes used for lighter-weight piping, especially types that are flexible enough to be supplied in coiled form.