The Android Operating System

We now begin with this course where we will look at some of the theoretical concepts around the development of applications for the Android operating system. We begin though, with an introduction to the Android operating system in general. So what exactly is the Android OS? Well, this is an OS which is based on a modified version of the Linux kernel and it is predominantly used for touchscreen mobile devices.

So you are more likely to find this on smartphones of course, and tablets, but also wearables and more recently, smart TVs, and some of the consoles available in cars. With that said. Let's take a very brief look at the history of Android. So this was a separate company which was founded in 2003 in Palo Alto, California in the United States. Originally, Android was meant to serve as an operating system for digital cameras. And you could make the argument that not much has changed in this regard, given the quality of cameras available on many mobile devices. What most people are aware of is the fact that Android is owned by Google.

And in fact, Google acquired it in 2005. This was a period where smartphones were still a niche product. And while the first iPhone was launched in 2007, the first commercial smartphone with the Android OS was the HTC Dream which came out in 2008. This was also known as the G1 in some markets and it had a physical keyboard. And the virtual keyboard which most of us should now be familiar with did not come out on Android phones until later. So what exactly are the features of the Android operating system?

Well, first of all, it is by far the most widely used operating system for mobile devices. Android claims that it powers over 2 billion devices. These include smartphones, tablets, smart TVs and IoT devices as well. We have already discussed the fact that this is something which is built on top of the Linux kernel. So it's not something built entirely from scratch. Another feature of the Android OS is the fact that its source code has been released by Google under an open source license. So if you'd like to build upon the Android OS, you can download the source code from the Android website.

If you do follow that route, it is important to know that Android uses something known as the Android Runtime as its runtime environment. And this uses something called ahead-of-time compilation in order to compile the application byte code into machine code. As far as Android applications are concerned, this translation from byte code to machine code is something which happens upon the installation of the app on the device and not while the app is running. This compilation ahead of time ensures better performance for the applications.

Moving along then to the different variants of the Android operating system. While the most common use case still involves users accessing this operating system from their smartphones. Android does have applications beyond just phones and tablets. For example, a variant of the Android OS is Wear OS. And this of course, is meant for wearable devices such as wrist watches, for example. If you have heard of Android TV, this also is based on the Android operating system.

This is something which is available on many smart TVs and it offers a similar experience to Android on mobile devices on a TV. Then there is Daydream, which is a platform for virtual reality devices and this is also something which is built on the Android operating system. And another flavour of the Android OS is Android Things and this is something which can be found in Internet of Things devices. The bottom line though is that the Android operating system is very flexible and can be adopted for a variety of devices.

When we begin the labs in this learning path, we will install our apps on a virtual device emulator. And while doing so, we will observe the data virtual devices available, not merely for smartphones, but also for wearables and TVs. And now that you have some understanding of the Android operating system in general, in the next video, we'll switch our focus to Android app development and the tools which are available for that purpose.