If you clicked on this blog and you're reading this, then I bet you have read many blogs and articles pertaining to audio mastering and you are still a bit confused. We were all confused at one point and this is why I'm going to explain it in a very dumb downed way.
You basically have 4 stages of music production, writing/arranging, recording, mixing and mastering. In my opinion, mastering is the most important, if you want it to stand out among the rest.
Let's start with the basic meaning of what audio mastering is
Where you take the stereo mix and fix any Frequency (EQ) deficiencies it may have.
Bring the volume up to an audio level that is as loud as every other released song for that specific genre.
Transferring and or converting the mix to its final medium, like a Gold master, Wav file or DDP image.
So you are basically doing EQ, controlling the dynamics and raising the overall volume of the mix.
The tools used for mastering are usually, EQ, Compressors, and Limiters
I find that the EQ should be able to process mid and side and left and right channels independently. So you have full control over the frequency field when editing the mix. You can use the Side EQ to make the stereo image wider and use the Mid for precise surgical EQ cuts and boost.
Are you asking yourself why i did not mention a multi-band compressor? If the mix needs a mutiband compressor, I would suggest that its not ready for the mastering stage. If you need something that drastic, it's best to fix it in the mixing stage. Now that is my opinion, but i arrived at that opinion through 30 years of experience. The same goes for any EQ edits over 3dB. If you have to cut or boost more than 3dB in the mastering stage, I would say that you should tell the client or yourself to go back and fix it in the mix. Audio mastering is a delicate process that involves subtle EQ cuts and boost.