Audio mastering is essential if the tracks are to compete in the music market. Mastered tracks are way ahead in terns of technology and sound clarity. What mastering does is to add clarity and professionalism to the sound tracks. A mastering engineer possesses a well equipped mastering studio and experience of listening to the songs. The experienced ears of mastering engineer can trace even the minutest details that may need correction and fine tuning. The music which is mastered well can go a long way. The mastering is done by tweaking the song wherever due. The engineer renders compression and Eq to make it sound, loud and clear. This is done without sacrificing on the dynamics of the sound track. When there is more than one track in an album, the master engineer listens to the whole album, as a single entity. The volumes are controlled to make the tracks sound uniform, the gaps between the tracks are also made uniform and each track is tweaked the best way possible. The background noises are reduced to make sure that the soundtrack is clear and professional. Now there are online audio mastering services as well, which make it easy for the customers to get their tracks mastered. The online services are much more affordable and easy to access. The service rendered is as good in quality as that attained through attended mastering. The growth of online services has led to high popularity of the mastering service. The musicians no longer think of releasing their tracks without getting it the polish that is mastering.