What is the definition of this word and full form GLBP,MSTP,RSTP,PVST?

GLBP -Gateway Load Balancing Protocol- Allows  router backup for multiple hosts

MSTP-Multiple spanning tree Protocol- Spanning tree instance can be defined in multiple  instance

RSTP- Rapid Spannin tree protocol - It will quicky converge to define the paths of the switching data

PVST - Per Vlan Spanning tree - Spanning tree is  defined per VLAN