Compressed files (like .zip, .rar, .7z) shrink data size and bundle many items into a single package, making storage and sharing easier.

They’re lossless: when you extract them, you get the exact originals back. Windows can handle basic ZIPs natively, while tools such as 7-Zip, WinRAR, and ALZip add power and formats.

Knowing common extensions and the right tool helps you move files faster, stay organized, and avoid headaches with big transfers.

In the last post, we looked at file extensions. This time, let’s talk about compressed files—those that end with extensions like .zip, .rar, or .7z.

File Size Basics

One of the first things we check when dealing with files is their size. File size represents how much space the file takes up on a storage device, measured in bytes (B). The units scale upward from KB (kilobyte), MB (megabyte), GB (gigabyte), to TB (terabyte). In Windows, right-click a file and select Properties to see its exact size.

Why Compress?

Large or numerous files are inconvenient to send or store. Compression bundles multiple files into one while reducing their size—like vacuum-sealing bulky clothes. Smaller bundles save storage and transfer faster, and they keep related items together for easier organization.

A Brief History

In the 1980s–1990s, storage was tiny and internet speeds were slow, so tools like PKZIP were essential to fit more data on disks and speed up transfers. Even today—with faster internet and bigger drives—compression remains a staple for efficient sharing and neat packaging.

Extracting (Decompression)

To use compressed files, you extract them. The data is restored to its original state through lossless algorithms, so the extracted files are identical to the originals—no quality loss.

Popular Tools

Windows supports basic ZIP compression/extraction out of the box. For advanced features or higher ratios, use:

• 7-Zip — free, powerful, widely used.
• WinRAR — strong compression and split archives.
• ALZip — popular in Korea with its own .alz format.

Common Archive Formats

• .zip — most common and highly compatible (Windows/macOS).
• .rar — strong compression and advanced features.
• .7z — open-source, efficient, flexible.
• .tar.gz — common on Linux (TAR for bundling, Gzip for compression).

Extensions hint at which tool you’ll need, so always check them before extracting.

Wrap-Up

Compressed files help you store less, send faster, and stay organized by shrinking data and bundling many items into one. From the early days of tiny disks to today’s fast networks, compression has remained a core skill. With ZIP, RAR, and 7Z in your toolkit, you can handle files more efficiently—even as a beginner.

You can view the original Korean blog post at the link below

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