A platter mat is a thin record-shaped material that sits on the turntable's platter and below the actual record. Its job is to hold the record firmly in place and absorb any extra vibrations that could cause distortion (unlike a "slip mat," which serves the opposite purpose for DJs). It's one of the last links in your hi-fi system's puzzle. And it's often overlooked.
Your turntable undoubtedly has a platter mat already, but it's an element you can easily and cheaply upgrade, for performance or aesthetic reasons. When buying a platter mat, there are two main things to consider. The first is the material of the platter mat. They are available in a number materials — such as felt, cork, rubber, leather and acrylic — and which you pick will impact effect the overall sound quality.
Felt is a good material because it's so cheap, but it's also more prone to static and slippage. Cork is a good and inexpensive option, but it's not the most durable. Rubber and Leather are both higher-end options because they're both durable and do a great job of sticking to the record.
That said, most people choose their platter mat based on how it looks. This is because, admittedly, unless you're an audiophile with a really fine-tuned ear, you probably won't be able to hear the difference. So it kind of comes down to how you want to show off your turntable when there's not a record being played.
Most turntables come with cheap felt platter mats, but if you're thinking about upgrading or replacing it, these are a few we'd consider.
Hudson Hi-Fi Corkery Recessed Platter Mat
Pro-Ject Felt Platter Mat
Fluance Rubber Platter Mat
Hudson Hi-Fi Acrylic Platter Mat
Pro-Ject: Leather It Platter Mat