So audio mixing is about realistic mix-ups of arts. It is all on the creativity of the person who does the job. But in all cases, the purpose is to make the sound relevant to the videos. Overall, sound mixing is done to make more interesting to listeners.
Audio mixing is done in studios as part of an album or single making. The mixing stage often follows the multitrack recording stage and the final mixes are normally submitted to a mastering engineer. The process is generally carried out by a mixing engineer (a mixer), though sometimes it is the musical producer who mixes the recorded material.
Prior to the emergence of DAWs (Digital Audio Workstations), the process of mixing used to be happen on devices known as audio mixer, sound board, desk, or mixing console. In modern times, more and more engineers and independent artists are using a personal computer for the process (commonly referred to as mixing in-the-box).
In films
Audio post production has different usage. A major one is with ADR. This stands for Automatic Sialogue Replacement. There are times when the real production audio is not so good in quality issues. In those cases, the audio post production will go back to the drawing board. This part is very interesting.
The real actors and actresses are called into the sound studio. Then the record or sound or dialogues are re-recorded from them. This can have other elements too. Good examples are foley, music, as well as voiceovers- as these things are added at this point.
Audio post production is also a common part of acoustic music recording.