Digital Compression
From WikiRecording
Digital compression, like most digital effects attempts to emulate the various properties of the analog gear found in recording studios. Most digital compresors have the same variables and knobs that you would find on the analog equivalent. Advanced Digital Compressors attempt to mimic the more unique flavors of famous compressors like the Bomb Factories BF76 (emulating the 1176 ).
A significant drawback to digital compression is the high amount of processing power required, even on top of the line computers adding more than a few Real Time Digital Compressors to an already complex project can reduce it to a stuttering mess. This is where dedicated audio processing cards like protools HD can be really helpful to expand the number of effects you can work with in a given project.
There are many freely available compressors that come with most DAW's, as well as some that are listed on the page: A Guide to Free Plugins
