What is a compressed zip folder? And why would you want to use them? Two excellent questions with answers that are quite straight forward, when you don't dive too far into the technical side.

What is Compressed?

A compressed Zip folder is pointing towards three things. The first is that it’s compressed, meaning a compression algorithm has done its work to reduce the target folder’s file size. We’ll explain this below, on how compressing a folder works.

What is Zip?

The second is that it’s a "zip," but what is a zip folder? A zip (or .zip as a file extension) is an archive file format, working with lossless data compression. Lossless data compression means that you don’t lose data in the compression process. Data in a zip file is encoded to take up less space on your hard drive, but as soon as you extract it, your original file is left intact.

Folder Compression Image

What is a Folder?

Folder, the last part points to a computer folder, a file directory often containing several single files. These files can be images, songs, executables, or any other computer file you can think of.

But how does it all work? Let’s discover the compressed zipped folder meaning.

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How does compressing a folder work?

When you compress a folder to zip, it works by applying certain compression algorithms to the files within the folder. The most common is the "DEFLATE" algorithm, a combination of LZ77 and Huffman codes.


To put it simply, LZ77 will look for sequences of data in your files that reoccur, which often is a lot. The algorithm then uses pointers to point back to where the reoccurring data has been seen before in your files.

This method effectively reduces file size by reducing the number of reoccurring bits of data. It can tell your computer that "it contains ten bits of this type of data," taking up one bit, rather than repeating that same data ten times, which amounts to 10 bits.

Huffman codes

Huffman coding is similar to LZ77. This algorithm further reduces file size by finding reoccurring bits of data and encoding them to take up less file space.

Together, these two algorithms work to compress a folder and the files inside, effectively reducing file size.

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Why compress folders

What is a zip folder used for, and why would you want to compress folders? Compressing a folder does three things.

Reduced file size

First and mainly, it reduces the file size, which saves you hard drive space. A zip file on your computer takes up less space than the original file, meaning you can store folders as zips and extract them when needed.

Convenient storage

Since zip files use lossless data compression, the original files will always be intact and restored to its original state once extracted. You can store folders within zip files too.

Faster online transfer

The reduced file sizes of the folders also work to increase transfer times online, sending several files within a folder to a friend, for example.

As you can see, there are many advantages to compressing zip files. Not only does it reduce file size remarkably, but it's also a great way to store your folders and share files online.

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