A .WRZ file is typically a gzip-compressed VRML scene, where a .WRL world file—containing text-based 3D data such as shapes, materials, lights, cameras, and occasional animations—has been reduced in size because VRML compresses extremely well, leading to the convention of naming these archives .WRZ or `.wrl.gz`, and the usual method of opening them is to decompress with something like 7-Zip or `gzip` to produce a .WRL that VRML/X3D tools can read, provided any texture images remain in the correct relative paths.

A straightforward check is verifying whether the file starts with the gzip indicator 1F 8B, a strong sign of gzip compression matching the WRZ format, and a common misunderstanding is mixing it up with RWZ, which belongs to Outlook Rules Wizard exports, so if the file came from email migration it may be RWZ, whereas anything from a 3D or CAD workflow is usually a true WRZ.

When someone says a .WRZ is a "Compressed VRML World," they mean that a standard VRML scene file—usually .WRL, literally short for *world*—has been gzipped to reduce space, since VRML uses structured text to describe full 3D scenes like geometry, materials, textures, lights, viewpoints, and basic behaviors, and because text compresses so effectively, the community adopted .wrl.gz and .wrz to indicate a gzipped VRML file.

In simple terms, describing it as a "compressed VRML world" means the file should be handled as gzip initially, producing a .WRL that VRML/X3D tools can still open, and the quick technical giveaway is whether its first bytes match gzip’s signature hex 1F 8B, which indicates it’s genuinely a gzipped VRML world rather than some unrelated file type using a similar extension.

Exploring a VRML "world" (the .WRL you get from unpacking a .WRZ) shows a scene graph of typed nodes describing visuals and user movement, with Transform/Group constructs managing transform hierarchies, Shape nodes merging geometry such as IndexedFaceSet with Material/ImageTexture appearance, and standard world components including Viewpoint cameras, NavigationInfo behavior settings, and bindable environment nodes like Background, optional Fog, and Sound.

VRML’s interactivity uses Sensor nodes like TouchSensor to send events, animations build on TimeSensor plus the Position/Orientation/Color/Scalar interpolators that provide time-based outputs, and ROUTE links connect everything, while complex behaviors rely on Script nodes with VRMLScript/JavaScript or occasional Java, and Anchor nodes allow hyperlink-like navigation, with the specification distinguishing transform-affected nodes from non-spatial ones such as interpolators, NavigationInfo, TimeSensor, and Script, giving the world the character of a small interactive program rather than a simple 3D model.

Calling a .WRZ a "Compressed VRML World" means the file isn’t a unique format but a standard VRML world (.WRL) stored as gzip to shrink download/storage size from the early web-3D period, leaving the VRML text intact—shapes, textures, lights, viewpoints, navigation, and simple behaviors—just packaged in gzip and signaled with .wrz or .wrl.gz, as noted by references like the Library of Congress, which is why 7-Zip/gzip opens it and why identifying the 1F 8B bytes helps confirm it’s really gzipped VRML.