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General Information About ZIP Files

ZIP files are compressed archives that group together one or more files into a single file. The ZIP file format is extremely popular for efficiently transferring files in a variety of business and personal applications.

The ZIP file format dates to the late 1980s when it received heavy use in pre-internet-era Bulletin Board Systems, or BBSes. In this era, they were referred to as PKZIP files from their original author Phil Katz (by PKWARE), and file transfers occurred using MODEMs and transfer speeds were very limited. ZIP compression regularly saved minutes or even hours off of any given file transfer.

Today, the ZIP file format remains in heavy use in the internet and in the cloud, with billions of such files estimated to be in circulation. In the cloud, ZIP files are common as both GMail attachments as well as files stored in Google Drive and other cloud-based storage systems such as Dropbox and Microsoft OneDrive.

In addition to compression, ZIP files’ principal benefit is that they can group together multiple files in a hierarchy. The path and folder information of the file tree is preserved. This makes the ZIP file format especially convenient for easily sharing and distributing groups of files.

Examples of ZIP File Uses

ZIP files have heavy usage across a variety of business areas, including the medical, insurance, legal, mortgage, banking and financial, scientific, equity trading, electric and gas utility, SEO (Search Engine Optimization), and education industries. Their benefits are applicable to employees and workers regardless of domain.

Here are some specific examples of uses of ZIP files across multiple fields:

  • A real estate agent could scan and ZIP together a sales contract and send to a listing agent in order to submit an offer.
  • An attorney could ZIP together a set of related legal documents such as a will, trust, or other estate planning documents and share them with their client for review.
  • An university student could ZIP a homework assignment and related files and send it to their instructor.
  • A tax accountant could ZIP and email a copy of a person's federal and state tax returns.

ZIP files can contain multiple files of different types, or can apply to just a single file. Common files that can be included in a ZIP archive include PDFs; images including PNG, JPEG, WEBP, BMP, GIF, and animated GIFs; video files such as MPG, MP4, MOV, and WEBM; Microsoft Office documents, including Microsoft Word, Microsoft Excel, and Microsoft PowerPoint (*.DOCX, *.XLSX, *.PPTX file formats). Some file formats are already compressed, such as PNG (Portable Network Graphics) files and certain MP3 audio formats. ZIP Extractor can preview all of these file types.

Creating ZIP Files

Most modern operating systems can create and open ZIP files. In Windows, to create a ZIP file, right-click on a file in Windows Explorer and selecting “Send to -> Compressed (zipped) Folder.” In Mac OS, create a ZIP file by right-clicking a file in Finder and selecting "Compress [name_of_file].” In a Chromebook or Chrome OS, choose one more more files in the Files app and then choose “Zip selection.”

These operations often referred to as compression and decompression, or more commonly zipping and unzipping. (In the technical domain, this is referred to as deflation and inflation.)

Once created on a local file system like Mac or Windows or Chrome OS, ZIP files can be automatically expanded (decompressed) by double-clicking them. Then, the individual files will be unzipped into a new directory and available to preview, edit, print, etc.

ZIP Files in the Cloud

ZIP Extractor provides the same decompressing functionality that standard operating systems provide, except that it works in the cloud. For example, there is no built-in ability to unzip ZIP files in Google Drive or GMail, so ZIP Extractor is a third-party application that provides this functionality.

The ZIP file MIME type, and the format that ZIP Extractor readily accepts, is ‘application/zip’. MIME types of ‘application/x-zip’ and ‘application/x-zip-compressed’ are also supported.

Encryption and Password Protection

The ZIP file format originally included support for basic password-protected ZIP files. More recently, the ZIP format was enhanced with the ability to create files with strong encryption, using AES (Advanced Encryption Standard).

ZIP Extractor supports opening certain password-protected ZIP files made with standard PKZIP encryption. Support for other encryption formats is coming soon.