Model your data using flexible combinations of key-value pairs, documents and graphs.
ArangoDB is a “document-oriented database”; it basically provides access to documents which are stored in collections. If you are new to nosql databases, think of documents as one row in a non-normalized table and of collections as tables for the time being.
Documents in ArangoDB are uniquely identified by keys, allowing key/value storage. They can be connected, allowing to treat and query them as graphs.
Documents can be very simple or as complex as you like, they can be nested and different types of indexes are supported.
Most other nosql databases do not support transactions. ArangoDB even supports cross-collection transactions.
A specialized binary data file format is used for disk storage. Documents that have similar structure (i.e., that have the same attribute names and attribute types) can share their structural information. Sharing the structure data between multiple documents greatly reduces disk storage space and memory usage for documents.