Facebook carries out 4.5bn translations a day, all using machine learning

"Creating seamless, highly accurate translation experiences for the 2 billion people who use Facebook is difficult. We need to account for context, slang, typos, abbreviations, and intent simultaneously. To continue improving the quality of our translations, we recently switched from using phrase-based machine translation models to neural networks to power all of our backend translation systems, which account for more than 2,000 translation directions and 4.5 billion translations each day. These new models provide more accurate and fluent translations, improving people's experience consuming Facebook content that is not written in their preferred language."

Source:  Blog post on the Facebook code blog, 3rd August 2017