In short and simple terms, the word "ar" is a verb form used to express or indicate an action being done in the present tense by a single person.
Sentences with «ar»
Android ™ 7.0 «Nougat» lets users get the most out of ZenFone AR with new multitasking features and other enhancements that deliver a great mobile experience (techlustt.com)
Another use of AR in the iPhone pertains to how users can utilize augmented reality in adding or placing virtual effects and objects on the person or subject of the image, just like how Snapchat's filters work. (ibtimes.com)