If we want our node to run on some particular browser like firefox or chrome driver etc we can firstand then the following command in our node

java -jar selenium-server-standalone-3.0.1.jar -role webdriver -hub http://localhost:4444/grid/register -port 5556 -browser browserName=firefox -browser browserName=chrome 

If we want a particular number of chrome or firefox or ie to run on our pc we can type ctrl+c to stop the above node and then type

java -jar selenium-server-standalone-3.0.1 jar -role webdriver -hub http://localhost:4444/grid/register -port 5556 -browser browserName=firefox,maxInstances=2 -browser browserName=chrome,maxInstances=3 -browser browserName=iexplore,maxInstances=2 

Now after typing the above command we see that we can run 3 firefox ,3 chrome and 2 ie browsers on our node.

But how many browsers we want to run concurently i.e together at the same time.For that we use max session

java -jar selenium-server-standalone-3.0.1.jar -role webdriver -hub http://localhost:4444/grid/register -port 5556 -browser browserName=firefox,maxInstances=2 -browser browserName=chrome,maxInstances=3 -browser browserName=iexplore,maxInstances=2 -maxSession 3