First, a fact: MongoDB is by far the world's most popular NoSQL database. That's an interesting fact, but it's not very helpful unless we understand why.
As for why MongoDB is so popular, Will Shulman, founder and CEO of MongoLab, nails it: "It's a data structure thing." As he notes,
The difference between the way we model things in code, via objects, and the way they are represented in persistent storage, via tables, has been the source of much difficulty for programmers....The document database, and in particular MongoDB, is the first successful Web-era object store, and because... Read More >