Multiple techniques and effects are used during the mastering process but some of the most important ones include:

Compression – This balances the track’s overall volume, raising up quiet dips and reducing loud spikes. Applying compression to the master is crucial in getting a sonically balanced song that is comfortable to listen to; yet also loud. This also helps to prevent clipping, which will widely prevent your song from being broadcast or distributed.

Loudness monitoring – for certain platforms, it’s crucial to make sure that audio submitted falls within the accepted loudness parameters. For example, if your audio is above a perceived loudness of -14db LUFS, Spotify will normalise your audio and either reduce or increase the volume.

Stereo enhancement – Another part of the mastering process is to ensure that your music sounds wide in stereo. Most music consumers will listen to audio through earphones or headphones and so making sure that your audio fills the full stereo range helps to create a more full and immersive sound.

Whilst these techniques may be used during the mastering process, the bulk of the work is done during the mixing process and mastering largely consists of final touches to get your song ready for distribution.