Sequencers are probably the most ubiquitous of audio and MIDI applications. A sequencer will be capable of storing a number of ‘tracks’ of MIDI and audio information, editing it and otherwise manipulating it for musical composition purposes. It is also capable of storing MIDI events for non-musical purposes such as studio automation. Some of the more advanced packages are available in modular form (allowing the user to buy only the functional blocks required) and in cut-down or ‘entry-level’ versions for the new user. Popular packages such as ProTools and Logic now combine audio and MIDI manipulation in an almost seamless fashion, and have been developed to the point where they can no longer really be considered as simply sequencers. In fact they are full-blown audio production systems with digital mixers, synchronisation, automation, effects and optional video.