Metaverse: This term accurately describes a network of interconnected, persistent 3D virtual spaces. 

Key characteristics of the metaverse often include:

• Interoperability: Users can move between different virtual worlds seamlessly.

• User-Generated Content: Users can create, own, and trade virtual assets.

• Social Interaction: The metaverse facilitates social experiences and interactions.

Let's look at why the other options are incorrect:

• Big data analytics: This involves analyzing large and complex datasets to uncover patterns and insights. It's not directly related to virtual worlds.

• Cryptography: This focuses on secure communication and data protection techniques. While relevant to security within a metaverse, it doesn't define the concept itself.

• Virtual matrix: This term is not commonly used to describe the concept outlined in the question. The term 'matrix' is often associated with a grid-like structure or a virtual reality environment, but not the broader interconnected network the question describes.