Google data centers in late 2013 and began selling off the barges in 2014. Most of the software stack that Google uses on their servers was developed in-house. According to a well-known Google employee, C++, Java, Python and (more recently) Go are favored over other programming languages. For example, the back end of Gmail is written in Java and the back end of Google Search is written in C++. Google has acknowledged that Python has played an important role from the beginning, and that it continues to do so as the system grows and evolves. The software that runs the Google infrastructure includes:
YouTube number of videos, can be downloaded as MP4 files. Numerous third-party web sites, applications and browser plug-ins allow users to download YouTube videos. In February 2009, YouTube announced a test service, allowing some partners to offer video downloads for free or for a fee paid through Google Checkout. In June 2012, Google sent cease and desist letters threatening legal action against several websites offering online download and conversion of YouTube videos. In response, Zamzar removed the ability to download YouTube videos from its site. Users retain copyright of their own work, but have the option to grant certain usage rights