Tatoeba is a large database of sentences and translations. Its content is ever-growing and results from the voluntary contributions of thousands of members.
Tatoeba provides a tool for you to see examples of how words are used in the context of a sentence. You specify words that interest you, and it returns sentences containing these words with their translations in the desired languages. The name Tatoeba (for example in Japanese) captures this concept.
The project was founded by Trang Ho in 2006, hosted on Sourceforge under the codename of multilangdict.
The video below, made in 2010, presents the core ideas of Tatoeba.