A channel strip is a device designed for the processing and line-level amplification of an audio source or instrument, allowing the signal to be used in a professional audio system such as a recording or a mixing environment.
Channel Strips are usually made up of an input or preamplifier section compatible with a variety of microphones and instruments, a sound altering section usually encompassing an equalizer and/or a compressor along with various other sections, depending on the specific purpose of the model.
Traditionally, channel strips were made available as replacement modules in large-format recording consoles. However, throughout the history of audio equipment, these units have been developed into a class of their own and can be found in a variety of shapes serving specific sources such as vocals, guitars and bass guitars.
Some of the main manufacturers of stand-alone channel strips include Focusrite, GML, Manley Laboratories, Millennia Media, Universal Audio, AMS Neve, Rupert Neve Designs and Aphex, among many others.
The main benefit of running your track through a channel strip is flexibility, since the unit will usually offer the main type of processing required for a particular instrument or microphone.