A syntactic dependency parse is a kind of shallow meaning representation. It's an important piece of many language understanding and text processing technologies. Now that these representations can be computed quickly, and with increasingly high accuracy, they're being used in lots of applications – translation, sentiment analysis, and summarization are major application areas.
To fully appreciate, understand and manipulate the embedded structure within language, it is often necessary to visualize that structure. I can only assume this is part of the reason why spaCy rolled out a demo visualization tool called DisplaCy a while ago.
Unfortunately, last I checked (July 23 2016), the displacy stage at spacy.io/demos/displacy returned a dreaded 404 error!!
It was a very useful reference for working with dependency trees in spaCy and I hope it will be coming back. In the meantime, seeing the despair of the NLP community I decided to replicate (if only partially) their work for anyone to use.