What is the difference between MemFree and MemAvailable in /proc/meminfo?

Question

cat /proc/meminfo
commad has given me below ouput,

MemTotal:       12136496 kB
MemFree:         9904872 kB
MemAvailable:   11123092 kB
Buffers:               0 kB

Can anyone tell me what is the difference between MemFree and MemAvailable?
Also why Buffer is showing as "0"?
Can anybody tell me what is buffer size?

Answer 1

MemFree: The amount of physical RAM, left unused by the system.

MemAvailable: An estimate of how much memory is available for starting new applications, without swapping. Calculated from MemFree, SReclaimable, the size of the file LRU lists, and the low watermarks in each zone. The estimate takes into account that the system needs some page cache to function well, and that not all reclaimable slab will be reclaimable, due to items being in use. The impact of those factors will vary from system to system.

Buffers: Temporary storage for raw disk blocks (it shouldn't get tremendously large and should be zero or very less)