As per Quartz in 2015, there are more than 24,000 different Android devices. This number is bound to grow exponentially, year by year considering the digital adoption and competition. You can't control which mobile or OS your users would use to visit your website or use your application. Also, Android continues to roll out newer versions and some users tend to not upgrade. Validating the user experience is pivotal for business stakeholders so it is important to test out on different versions of Android.