Mastering can raise your album's overall level through the careful use of compression, so your album can compete with any major label release. The Mastering engineer also ensures that your music will sound great - whether it's being played through a car stereo, a portable CD player, or a top-of-the-line stereo system. In Mastering, the sound of your CD will be optimized, making it sound punchy, warm, and full, while raising the overall level (volume) and highlighting details that aren't already apparent. Mastering is also helpful for addressing issues such as "pops," out-of-phase tracks, and overall noise reduction.