Volume Boot Record
A Volume Boot Record (VBR) is the first sector of a partition (opposite to MBR which is the first sector of a hard disk). VBR (just like MBR) also contain some code and data, but it's far less standard. Instead of Partition Table it usualy holds some FS info, like the BIOS Parameter Block (although it's not needed nowdays, many OS have kept it for compatibility). The code is always OS specific, but in common all versions does the same: locate the kernel on the partition, load and execute it. A really good example for VBR is the original DOS bootsector, which knew FAT and loaded IO.SYS and MSDOS.SYS from the root directory.
This is file system specific, but usual has a JMP followed by FS info.