Ornithology (from Greek: ὄρνις, ὄρνιθος, ornis, ornithos, "bird"; and λόγος, logos, "rationale" or "explanation") is a branch of zoology that concerns the study of birds. Several aspects of ornithology differ from related disciplines, due partly to the high visibility and the aesthetic appeal of birds. Most marked among these is the extent of studies undertaken by amateurs working within the parameters of strict scientific methodology.