For example: Xiao Ming go to restaurants line up to order, the clerk will Xiaoming menu to tell the chef for production, this time behind Bob queue of people have been waiting until the cook finished, the meals to the hands of Xiao Ming left behind the people to continue ordering; this is the synchronization process; however, if the clerk would Xiaoming menu to tell the chef, the waiter sent Bob a good card to go next to the waiting, the people behind the continued ordering, chef Bob meals do after, feel free to call Bob meals; this is the asynchronous processing
of different approaches servers, on behalf of Ajax synchronous or asynchronous processing;
Xiao Ming is the client;
the chef is the background server;
