We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is Data Compression?

By R. Kayne
Updated May 16, 2024
Our promise to you
EasyTechJunkie is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At EasyTechJunkie, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

Data compression is a general term for a group of technologies that encode large files in order to shrink them down in size. Smaller files take up less room, leaving more storage space. They are also faster to transfer over a network, whether that network is the Internet, an intranet, or a local area network (LAN).

In the 1970s, various techniques were available to archive files, or place them together in a single package to avoid sending multiple files between computers. The idea was soon augmented with data compression techniques, so the term “archive” is now often used to describe a compressed file.

Compressing data involves applying an algorithm that makes some of the repetitive bits unnecessary. It's a bit like a kind of shorthand map that gets stored with the compressed file. When decompressed, the map restores all of the missing bits, reconstituting the complete file. This technique can be used with text, graphics, executable programs, and multimedia files, though some types of files compress better than others.

Today’s most commonly recognized data compression technique was originally used in the DOS operating system prior to Microsoft Windows™ becoming ubiquitous in the mid-1990s. Author Phil Katz eventually termed these compressed files zipped files — the idea being that when the files were unzipped (decompressed), the full contents “popped” out. Files used with this method have the extension, .zip.

Files that are extremely large even when compressed can be split into pieces before being sent over a network. The pieces are collected and reassembled on the receiving end. The leading compression technique for large files, also from the days of DOS, is called RAR, after author Eugene Roshal. Programs that support Roshal ARchive files can create a set of RARs from a large multimedia file, for example, or decompress an existing RAR to reassemble a movie or program. These files have the extension .rar, or for multi-part files, part01.rar, part02.rar or .r01 r02.

Various music formats also use other data compression techniques to shink the files while maintaining as much of the original quality as possible. The most obvious example is the .mp3 format. In this case, however, the compressed file is not an archive and cannot be decompressed. The bits that are removed to achieve the smaller file size are gone for good. Other techniques used for music files retain more quality but also result bigger file sizes.

Data compression programs are widely available online. A zipped or RAR'd file requires a program that supports that method to unzip or unRAR it. Most programs support multiple types of compressed files, and many of these programs are freeware.

EasyTechJunkie is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Discussion Comments
By Melonlity — On May 14, 2014

@Terrificli -- while pirates do love compressing movies and songs to smaller files so they can be shared on the Internet, those technologies don't benefit just people wanting to download entertainment and not pay for it. For example, most old time radio (OTR) programs are available on the Internet in MP3 format. Often, we're talking about shows such as "The Jack Benny Program" or "Burns and Allen" that are effectively public domain and might have been lost had they not been converted to digital formats that don't deteriorate. The MP3 format, then, has been essential in preserving those old shows. No illegality there.

Also, there are a good number of independent bands and filmmakers that have taken advantage of file compression to share their creations easily with others.

Indeed, there is a problem when compression is used to share files illegally, but none when it is used to make sharing files that are public domain or compressed and made available by the people who own the material or have the right to use it. It all goes to the intention of the user as to whether an MP3, MP3, AVI or anything else is legal or not.

By Terrificli — On May 14, 2014

@Soulfox -- yes, you will lose some video quality with those formats. That is because MP4, AVI and several others save space the same way the MP3 format does. They are called "lossy" formats because some information is stripped out in an attempt to make files small enough to download. There are some digital formats that are not lossy, but they result in large files and are rarely used.

Here's the good news, thought. The loss in quality is hard to detect by most people. You get a picture and sound that is, in most cases, more than good enough so people don't mind the loss in quality.

That is exactly why piracy is so rampant these days -- big old movies and songs can be shrunk down to sizes that are manageable and downloadable.

By Soulfox — On May 13, 2014

The same is true of video. When you see file extensions such as MP4 or AVI, you are looking at a file that carries video and is considerably smaller than the original.

Here's a question. This article points out how MP3 files are audio files that are smaller than the originals but sacrifice quality for size. Is the same true of MP4, AVI and other file formats that carry video?

EasyTechJunkie, in your inbox

Our latest articles, guides, and more, delivered daily.

EasyTechJunkie, in your inbox

Our latest articles, guides, and more, delivered daily.