Why do I need an Audio/MIDI Sequencer?
The audio/MIDI sequencer (a.k.a. recording software, audio/MIDI studio, DAW - Digital Audio Workstation, or audio host) is the control center for modern music production. It offers a practically unlimited number of audio and MIDI tracks for recording or arranging sounds and sequences, numerous editing tools, a virtual mixing desk and integrated effects.
Multitrack-hard disk recording
Instruments can be recorded directly through the inputs on your sound card. Hard disk recording replaces the earlier tape machines. Limitless editing of recorded material is possible.
Import audio data
Instead of recording on your hard disk you can also import finished audio samples (from sample CD-ROMS for instance), like whole bass lines or keyboard phrases.
a) Integration of software instruments: Software instruments (e.g. from Native Instruments) can be opened and played as a plug-in, the MIDI (or audio) data can be recorded and edited. The so called "automation" makes it possible to record the movements of all software instruments knobs and faders while playing.
b) External MIDI instruments (like hardware synthesizers) can be integrated and controlled remotely with your sequencer.
Arrange and Edit
The recorded MIDI and audio tracks can be rearranged, copied, shortened and edited in many ways, so that you can come to a complete song arrangement.
Many sequencers have integrated effects like hall, EQ, delay and compression. NI effect plug-ins (e.g. VOKATOR, NI-SPEKTRAL DELAY, REAKTOR) can be plugged in as well. Individual tracks or the entire signal can be processed with effects.
A virtual mixing board regulates the volume relationship and the stereo pan between tracks. Level and pan changes can be recorded (automation), so that for example you could blend a specific track in and out.
Mix down ("audio export" or "bouncing").
A finished song with many tracks can be exported as stereo audio data (WAV or AIFF format), i.e. written to the hard disk. This stereo audio data (your songs) can be burned directly to a CD with a burning program. Your first CD is finished.
Some sequencers also allow direct note input, and the presentation of the recorded MIDI data as notes in a number of different notation types.
Dedicated Notation software is available from the likes of Sibelius.