The ARA phone is “modular”, i.e. parts of it can be swapped out and new attachments can be added. For example, if you want more storage, you can swap your old storage module with a new one! Or if you want a larger camera, you can swap the speaker module with a better camera module. And of you break your screen, you simply replace the screen module with a new one - and perhaps upgrade the quality of the display!
Project ARA has had lots of ups and downs. It was initially initiated by Motorola when it was a part of Google, and when Motorola was sold to Lenovo the project was handed over to Google ATAP. Last year, ATAP scrapped plans to test-drive the phone in Puerto Rico as they had to overcome technical hurdles and lower costs. The Head Engineer of ARA also left to join Airbus.
The news comes as a huge surprise and disappointment, especially following Google ATAP’s announcement at Google I/O in May 2016 that a developer version of Project ARA will be released this fall. Now, Google suspend the project because it was too ambitions and extremely costly.
Motorola/Lenovo's Moto Z with it’s interchangeable backplates will likely be as close as we can get to “modular” smartphones.
Dave Hakkens, the creator of the PhoneBloks concept, is definitely sad. But he was right: ARA wasn’t a pure derivation from the PhoneBloks concept, as he pointed out in this Facebook post from May 2016 (Google I/O):