Grouping in Selenium

http://www.tutorialspoint.com/testng/testng_group_test.htm

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd" >

<suite name="Suite1">

   <test name="test1">

      <groups>

         <define name="all">

            <exclude name="functest"/>

            <include name="checkintest"/>

         </define>

         <run>

            <include name="all"/>

         </run>

      </groups>

      <classes>

         <class name="GroupTestExample" />

      </classes>

   </test>

</suite>

Other Links:

1. http://www.toolsqa.com/selenium-webdriver/testng-annotations-groups-depends/
2. http://learn-automation.com/how-to-group-testcases-in-selenium/
3. http://testng.org/doc/documentation-main.html#methods

Read More: 

1. http://www.mkyong.com/unittest/testng-groups-example/
2. http://stackoverflow.com/questions/23888753/please-explain-paralle-and-grouping-execution-using-testng-and-explain-the-code