A 64-byte data structure that defines the way a PC's hard disk is divided into logical sections known as partitions. While there is often more than one partition table on a PC's hard disk, the most important is the one stored *in* the MBR. This one contains important extra information such as which partition (if any) should be booted from. The partition table is purely data, so is not executed. Some people erroneously use the term "partition table virus" as a synonym for "MBR virus".