MySQL to add to cart 1-4 Socket Server When I check for price tags for MySQL, I see a clause called "1-4 socket server" or "5+ Socket Server".. what does this mean? 

"Socket" in generic term means Inter Communication Protocol. For MySQL, a socket unix file helps to communicate between MySQL server and MySQL client within local server, and there is only one as far as I know per MySQL server instance. 

Please correct me if my understanding is wrong. Kindly shed some light what is meant by 4, 5+ sockets as I see cost increases as socket numbers rises.  Also, what are the advantages of the higher sockets?
Socket here means physical CPU plugged into the motherboard.

Note that a single socket will consist at least one "core".

From the MySQL products page:


  5 Socket: is defined as a slot that houses a chip (or a multi-chip module), which contains a collection of one or more cores. Regardless of the number of cores, each chip (or multi-chip module) counts as a single socket. All occupied sockets on which the Oracle programs is installed and/or running must be licensed.


** I use "plug" loosely nowadays of course