The phrase usually refers to a compressed archive file (using the .7z or 7-Zip format) containing a collection of digital origami diagrams, crease patterns, or instructional PDFs.
Full instructional books or independent magazines. Origami Patterns 7z
Compressed files originating from public file-sharing forums or peer-to-peer networks can sometimes hide malicious software. Always run a downloaded .7z file through your antivirus software before extracting it. The phrase usually refers to a compressed archive