The Android OS is a mobile operating system developed by Google, based on a modified version of the Linux kernel and other open source software and designed primarily for touchscreen mobile devices such as smartphones and tablets.
The statement above should be written in a quoted box since you've taken an exact word-by-word definition from Wikipedia. It's good that you link the definition to the original source but it would be neater if it is put in a quote box.
Even if you have quoted every single source by embedding the article's link to a few sentences, you still need to list up our references at the end of your article.
You have some issues with your images, apart from what is yours, the second image can't be used because it is copyrighted while the third image was not properly credited.
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- The statement above was taken from the source of your 2nd image. Unless you have obtained written permission, you weren't allowed to use the picture.
RE: Using an Android 4.4.4 smartphone in 2018