Tremor is the shaking movement of the whole body or just a certain part of it, caused by problems of the neurons responsible from muscle action.

Tremor may occur as an isolated symptom and usually of unknown cause (essential tremor) or a part of the symptom constellation of another disorder (Parkinson's Disease). Tremors may occur at rest (Parkinson's disease), during voluntary movements (cerebellar lesions) or during excessive activity of muscles (essential tremor, hyperthyroidism). Tremors may increase with anxiety and caffeine and cease during sleep. Medications are used only if tremor interferes with daily life activities. Some of the drugs that can be used are clonazepam, mysoline, and propranolol.

Tremors are also the shaking movements of earthquakes.

Tremor is the name of a software library that decodes the Ogg Vorbis audio format. It is open source software released under a BSD-style license. Tremor uses fixed-point numeric representations in its implementation so that it can be used by small embedded devices (which typically do not have floating-point processors). Thus, Tremor enables small embedded devices to play audio files stored in the Ogg Vorbis format. Tremor was developed to encourage wider use of the Ogg Vorbis format.