Wow, big question :-)
I'll summaries it for you and you can use the links you had from previos posts
VRF is virtual routing and forwarding.
VRF forms a virtual isolated FIB and RIB inside a router thus any other VRFs or the router's global FIB&LIB (AKA VRF default) doesn't familiar with.
Commonly use in MPLS/VPN implementation to carry routes from VPN's customers, but can be used over IP which known as multivrf or vrf-light.
Hope it's been informative
Regards,
Yigal
