What’s a ZIP file anyway?

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A lot of people have HEARD of “zip files” but are not really familiar with what they are specifically. Here’s how they work.

zip file

Part of the confusion with this is that it’s not really obvious or clear what is meant by a folder being “zipped”. I mean, everyone knows what a zipper does, but how does that relate to computer files?

It might be easier if “zipped” were replaced with the word “compressed”. A zipped folder is just a folder that holds other files or folders, but compresses them so that they take up less space.

Think of it like this. Imagine you’re out camping, and you spend the night in your sleeping bag.

sleeping bag spread out


When you wake up in the morning and you’re packing up to hike for the day, do you just scoop up the sleeping bag and start stuffing it into your backpack? Of course not. It’s going to take up too much space, and it will be awkward and frustrating to carry it around like that.

Instead you carefully and strategically fold it, then roll it up to be as small and compacted (compresses) as possible:

sleeping bag compressed


Now you can fit it in your backpack for easy transport, and still have room for all your other essentials. I love efficiency!

A zipped/compressed folder does pretty much the same thing.

Let’s say you have a folder on your computer, and there are 20 pictures in that folder. You want to send those pictures to someone through email. Well, it would be pretty cumbersome to attach 20 pictures to an email. Or send 20 emails, each one with an attached photo. (Really, sending pictures by email is a bad idea to start with, but that’s a story for another day.)

Instead, you could “zip” all 20 photos into a single folder, then just attach that one zipped folder to your email. Not only is this more efficient, it’s actually going to be a smaller overall file size. The 20 pictures might have a total size of 9 mb, but compressed into a single folder you might have a total size of 7 mb.

The email recipient gets the email and opens the zipped folder (we’ll talk about this process in a minute), and there are all 20 pictures.

Another practical use: You have thousands of pictures and you want to put all of them on a little flash drive to carry with you, but your flash drive is an older one that only holds 4 GB. Putting the pictures on there directly would mean they wouldn’t be able to fit. But in a zipped folder, you can get them all on there.

You also sometimes see zipped files being used on websites, for downloading software. Rather than having you download the full (uncompressed) file, the website might offer the option of downloading a zipped file. Since that file size will be smaller, the download will be faster.

Here’s how you can create your own ZIPPED folder:

First, you start with a folder on your computer that has several files in it. This can be a folder full of Word documents, or PDF files, or pictures. Doesn’t really matter what type of files you use.

With that folder open, hold down CTRL and tap the letter “a”. This highlights all of the files.

Now, do a right click on one of the highlighted files and choose Send To – Compressed (zipped) folder.  You’ll see a new folder there on your screen. That’s your newly-created zipped folder, and it has all those files in it (even though you still see all the files in the same place they were in that folder already). That’s how easy it is!

Now you can do whatever you want with that zipped folder. And if you delete the zipped folder, all of your original files will still be in the original folder just like they were when you started.

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Glyn Hunt
January 8th, 2018

How do you deal with a zipped file received?

January 8th, 2018

Excellent program! You stated a ZIP file is one which has been compressed. There are many different types of compressed files (or folders). One which you did not mention is the RAR file. ZIP comes with Windows, while RAR has to be installed. Once installed, RAR can handle both ZIP and RAR files and compresses to a smaller size. Users should check out the RAR program as well as ZIP because they are sure to encounter it in their online activities. USEnet is one example where they are widely used instead of ZIP. Another compression program is called 7-ZIP, It is open-source (FREE) and can handle several types of compressed files.

Scott Johnson
January 8th, 2018

Glyn – I deal with zip file attachments just like any other attachment. I don’t open it unless I already know what it contains. Zip files can contain bad things, like any other email attachment.

Linda J Sickle
January 8th, 2018

I have a similar question to Glyn. When you identify that it is a folder you want to open how do you do that with a zipped file? I’ve sent things to people before this way and they could not open them. Is there a secret way to do this?

Scott Johnson
January 8th, 2018

If you’re using Windows (any version since Windows XP), you can open a ZIP folder with File Explorer. You don’t need any third party software.

Ingrid B
January 14th, 2018

If you can ‘open’ a ZIP folder with File Explorer (i.e. without 3rd Party Software), can you also ‘create’ ZIP folders without 3rd Party Software? I purchased a well known ZIP Software a year ago, and I’m regularly receiving email offers for a 50% discount if I ‘upgrade the the latest version NOW’. I’m beginning to think I never needed it in the first place (running Win10). Thanks for your always invaluable tips.

Scott Johnson
January 14th, 2018

Yes, the blog post gives specific instructions on how to create a ZIP folder just using File Explorer. You don’t need WinZip or any other software to do this.