In chemistry, especially biochemistry, a fatty acid is a carboxylic acid with a long aliphatic tail (chain), which is either saturated or unsaturated. Most naturally occurring fatty acids have a chain of an even number of carbon atoms, from 4 to 28. Fatty acids are usually derived from triglycerides or phospholipids. When they are not attached to other molecules, they are known as "free" fatty acids. Fatty acids are important sources of fuel because, when metabolized, they yield large quantities of ATP. Many cell types can use either glucose or fatty acids for this purpose. In particular, heart and skeletal muscle prefer fatty acids. The brain cannot use fatty acids as a source of fuel; it relies on glucose or ketone bodies.

Fatty acids that have double bonds are known as unsaturated. Fatty acids without double bonds are known as saturated. They differ in length as well.

Fatty acid chains differ by length, often categorized as short, medium, or long.

Unsaturated fatty acids have one or more double bonds between carbon atoms. (Pairs of carbon atoms connected by double bonds can be saturated by adding hydrogen atoms to them, converting the double bonds to single bonds. Therefore, the double bonds are called unsaturated.)

Kruder & Dorfmeister, named after members Peter Kruder and Richard Dorfmeister, is an Austrian duo most known for their downtempo-dub remixes of pop, hip-hop and drum and bass songs.

Their mixes are usually flavored with sampler-processed vocals, deep bassline dub, trip-hop elements, bossa grooves and smoothly-shaped echoes. Some of their better-known works include "High Noon," "Original Bedroom Rockers," and remixes of Madonna's "Nothing Really Matters," Depeche Mode's "Useless," Count Basic's "Speechless" and Roni Size's "Heroes". Many of their remixes are collected on the double album The K & D Sessions.

Although best known internationally for their remixing work, the duo gained their primary reputation in Europe for their live DJ performances and their DJ mix album for the DJ Kicks series DJ-Kicks: Kruder & Dorfmeister. Kruder and Dorfmeister have their own recording studio in Vienna, and label G-Stone Recordings through which they release many of their own albums.

Richard Dorfmeister vs. Madrid De Los Austrias (w/ Heinz Tronigger & Michael "Pogo" Kreiner)