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Compression is not only helpful when sharing large files, but also makes it easier to work with collections of files as a single compressed bundle. 

There are many compression tools and software options. This Data Nudge presents four common compressed (zipped) file formats that are widely used in research.


 4 common compressed/zipped/grouped file formats used in research

ZIP (.zip): The most commonly used compressed format.
              Highest compression speed but lowest compression ratio
              Built in to Windows machines
               Common on Linux/Posix systems

TAR (.tar): Used to store multiple files in a single file, sometimes referred to as a "tarball."
              Does not compress
              Can simplify handling and transfer of complex directory structures
               Common on Linux/Posix systems
               Can be used on Windows using 7-zip or on Mac OS X using Unarchiver

GZIP (.gz): Used to compress tar archive files. The .gz file extension may be preceded by another format extention, for example .tar.gz (sometimes shortened to .tgz) or .txt.gz. 
              High compression speed and slighly higher compression ratio than ZIP
              Common on Linux/Posix systems
              Can be used on Windows using 7-zip or on Mac OS X using Unarchiver

7Z (.7z): A high compression format. 
              Highest compression ratio but slowest compression speed
              Can split one archive into smaller chunks
              Common on Windows, Mac OS X, and Linux
               Command-line version can be used in Linux/Posix using p7zip
              Can be used on Windows using 7-zip or on Mac OS X using Unarchiver  


When files do NOT compress well

Other files and most multimedia often will not compress well because they already exist in highly compressed states, examples include but are not limited to: 
              ⚠ audio (MP3, WMA, etc)
              ⚠ video (AVI, MPG, etc)
              ⚠ image (JPG, PNG, GIF, etc)
              ⚠ encrypted files

Therefore, you won't see the kinds of space-saving compression results as you would experience with text files or other previously-uncompressed formats. In fact, it can even get bigger.


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