Bitcoin core config explanation I'm just not understanding what does the following arguments do! 

-dbcache : Set database cache size in megabytes (4 to 16384, default: 300)


  which database is that? and what may happen if the file size excessed
  16384 megabytes.


-par=N  Set the number of script verification threads (-2 to 16, 0 = auto, &lt;0 = leave that many cores free, default: 0)


  What is script verifications threads? may this affect performance? 


-pid= Specify pid file (default: bitcoind.pid)


  what is this for?


-bind=    Bind to given address and always listen on it. Use [host]:port notation for IPv6


  is this for RPC calls, so bitcoin core listens only to given IP address?


-discover   Discover own IP addresses (default: 1 when listening and no -externalip or -proxy)


  what do they mean? 


-upgradewallet  Upgrade wallet to latest format on startup



  what is the wallet formats?


-rpcbind=&lt;addr&gt; Bind to given address to listen for JSON-RPC connections. Use [host]:port notation for IPv6. This option can be specified multiple times (default: bind to all interfaces)



  when we Bind to IP address, will the software listens to this IP address only? 


-rpcthreads=&lt;n&gt; Set the number of threads to service RPC calls (default: 4)



  how many connections can a thread afford? and how the connections counted? is it per IP address or command?
-dbcache: bitcoin is doing heavy disk I/O, you can reduce disk I/Os with increasing this parameter and thus increase memory usage

-par: if your system is so slow, you can't use it anymore, limit the number of threads or CPU/cores that are used

-pid: this is usually the process ID on your unixoide system. if you start a single instance, there is nothing to play with...

-bind: if you have several network cards in your system, you can bind the process to one of the many IP addresses in your system

-discover: discover IP addresses in the network. Set to 1, else set to 0, e.g. if you are using connections over TOR. 

-upgradewallet: - someone else please :-)

-rpcbind: if your system is multihomed, and you want to talk from several networks to your machine, you can tell the bitcoin daemon, to listen to only a specific address for remote procedure calls

-rpcthreads: 


  how many connections can a thread afford?  


good question, I don't know. Experts please. I was of the opinion, that one thread can handle one connection... 


  and how the connections counted?


not sure what you mean by this - if you have 4 clients, that connect to your system, then you have 4 connections. Or 5... or 6 ... and you can have 4 different systems talk to your bitcoind.


  is it per IP address or command?


per IP address.

I know my answer is not 100%, so I am asking for additional help as well.