unzipping

Unzipping is the process of extracting the contents of a compressed archive, most commonly a ZIP file. It reverses the compression and packaging performed by zipping, restoring the original file names, directory structure, and metadata. While ZIP is the format most closely associated with unzipping, many other archive formats such as tar.gz, 7z, and RAR involve a similar extraction step.

How it works: An archive gathers multiple files and directories into a single container and applies a compression method to reduce size. Unzipping reads the archive’s metadata, verifies data integrity, decompresses the content, and writes files to a chosen location. Some archives support encryption and password protection, in which case extraction requires the password. Extraction may also preserve or adapt file permissions and timestamps, depending on the tool and format.

Tools and platforms: Unzipping is supported by a wide range of software. Common tools include the unzip utility on Unix-like systems, File Explorer on Windows, and Archive Utility on macOS. Third-party options include 7-Zip and WinRAR. Typical actions include selecting an archive and choosing extract, or using command-line commands such as unzip archive.zip or unzip -d /destination archive.zip; on Windows PowerShell, Expand-Archive can be used.

Security considerations: Extracting archives can pose risks if the archive contains malware or attempts directory traversal attacks that write files outside the target directory. Users should obtain archives from trusted sources, scan for malware, and extract into a dedicated folder with sufficient permissions and space. Be cautious of encrypted archives and password compromise.

History and scope: The ZIP format was introduced in 1989 by Phil Katz and PKWARE and remains the most common target for unzipping. The term can apply broadly to decoding or extracting data from various compressed archives, not just ZIP.