Selenium webdriver scripts using selenium grid code example

Example 1: selenium grid

Selenium Grid can be used to execute 
same or different test scripts on
multiple platforms and browsers
concurrently so as to achieve distributed test execution.

It allows running test cases in parallel
thereby saving test execution time.
It allows multi-browser testing.
It allows multi-OS testing.
It allows multi-platform testing (desktop, mobile).

Example 2: what is hub in selenium grid

A hub is a server or a central point
(Point of Contact) that controls the
test executions on different machines.