Selenium Grid enables you to spread your tests across multiple machines and multiple browsers, which allows your to run tests in parallel. Also having Hub as central point of communication handles all the driver configuration and runs them automatically.
http://docs.seleniumhq.org/download/
Once you have the jarfile downloaded from the Selenium Website,
java -jar selenium-server-standalone-2.x.x.jar –role hub
This starts up a jetty server on default port 4444. Grid Console can be viewed at http://localhost:4444/grid/console
Nodes are the actual machine which performs the tests,
java –jar selenium-server-standalone-2.x.x.jar –role node –hub http://hubIP:4444/grid/register
java -Dwebdriver.ie.driver=C:/eclipse/IEDriverServer/IEDriverServer.exe -Dwebdriver.chrome.driver=C:/eclipse/chromedriver/chromedriver.exe -jar selenium-server-standalone-2.48.2.jar -port 5555 -role node -hub http://localhost:4444/grid/register -browser "browserName=firefox, maxInstances=10, platform=ANY, seleniumProtocol=WebDriver" -browser "browserName=internet explorer, version=11, platform=WINDOWS, maxInstances=10" -browser "browserName=chrome,version=ANY,maxInstances=10,platform=WINDOWS"
java -Dwebdriver.ie.driver=C:/eclipse/IEDriverServer/IEDriverServer.exe -jar selenium-server-standalone-2.48.2.jar -port 5555 -role node -hub http://localhost:4444/grid/register -browser "browserName=internet explorer,version=11,platform=WINDOWS,maxInstances=10"
java -Dwebdriver.chrome.driver=C:/eclipse/chromedriver/chromedriver.exe -jar selenium-server-standalone-2.48.2.jar -port 5556 -role node -hub http://localhost:4444/grid/register -browser "browserName=chrome, version=ANY, maxInstances=10, platform=WINDOWS"
java -jar selenium-server-standalone-2.48.2.jar -port 5557 -role node -hub http://localhost:4444/grid/register -browser "browserName=firefox, maxInstances=10, platform=ANY, seleniumProtocol=WebDriver"