What is patition boot sector?

A partition boot sector is a region (typically the first 512 bytes) of a partition (i.e., a logically independent section of a HDD), that contains information for booting (i.e., starting up) an operating system that is stored on that partition. It is usually at the beginning (first sector on a hard disk drive). And the term is often used to refer to the master boot record (MBR), which occupies the first sector of a Hard disk drive, although each partition can have a boot sector.

See: Disk Partition, MBR, Partition Table