Somebody has sent you a file with a zip icon on it. Or you downloaded something and got a folder that will not quite open like a folder. Or a website is telling you to install a program before you can see what you already have.
That last one is the part worth stopping on. On a current version of Windows you very likely do not need to install anything at all.
So here is what a zip file is, and what your PC already does with it.
What it is
A zip file is one file holding other files inside it, squeezed down to take less room than they do on your machine.
Two reasons it exists. It makes things smaller, so they reach you faster. And it turns many files into one, which is why people email a zip rather than forty separate attachments.
⭐ The squeezing is lossless. What you get out is byte for byte what went in. Unlike a photo saved at lower quality, nothing is thrown away to make it smaller.
Ours, and marked as ours: how much smaller depends entirely on what is inside. Text and spreadsheets shrink enormously. Photos, videos and music barely shrink at all, because they are already compressed.
A zip full of holiday photos being the same size as the photos is normal, not a fault.
Opening one, with nothing installed
Microsoft's own instruction is one line: "right-click (or press and hold) the folder, select Extract All…, and then follow the instructions."
That is it. I know it looks too simple, and Windows has done this without extra software for over twenty years.
You can also open a zip by double-clicking it and drag single files out. Microsoft describes that too: "drag the file or folder from the zipped folder to a new location".
⚠️ Dragging one file out works, and browsing without extracting has a catch. Some programs cannot open a file that is still inside the zip, and you get a confusing error. If something misbehaves, extract properly first and then open it.
Making one
Microsoft's route: "Right-click (or press and hold) the file or folder, select Show more options > Send to > Compressed (zipped) folder."
Select several files first and they all go into one.
The part that changed, and why you can stop installing things
For years, zip was the only format Windows handled. Anything else meant downloading a program.
That is no longer true.
Documented by Microsoft on its zip and unzip page: "Windows 11, version 24H2 supports ZIP, RAR. 7z and TAR archive formats."
⭐ RAR and 7z, built in. Those are the two that used to force people into WinRAR and 7-Zip. On a current Windows 11 they open the same way a zip does, by right-clicking and choosing Extract All.
Ours, and marked as ours: if you have been paying attention to a WinRAR nag screen for years, check your Windows version before renewing anything. Settings, then System, then About, tells you which version you are on.
The one case where you still need a separate program
And Microsoft is clear about it.
Documented by Microsoft: Windows 11 24H2 "does not support operations on encrypted archive files."
So a password-protected archive still needs 7-Zip or WinRAR. Everything else does not.
⚠️ Password-protected archives are common in two places: files sent by people who want them private, and files sent by people distributing malware, because a password stops security software looking inside.
If an unexpected email includes a password-protected archive and helpfully gives you the password, that is the pattern, not a courtesy.
The warning nobody prints, and it is Microsoft's own
⛔ This one is worth reading twice if you handle anything sensitive.
Documented by Microsoft: "If you add encrypted files to a zipped folder, they'll be unencrypted when they're unzipped, which might result in unintentional disclosure of personal or sensitive information."
⭐ In plain terms: zipping an encrypted file strips the protection off it. You put a locked thing in, and whoever unzips it gets an unlocked one.
If you have ever zipped up a folder of protected documents to email them, that is what happened.
When a zip will not open
Three causes, in the order they actually happen.
The download did not finish. A partial zip fails on the last step, and the error usually mentions the file being corrupt or unexpected. Download it again before anything else.
Where the drive is short of room rather than the file being awkward, why a full drive slows everything covers why a full drive bites.
It is not really a zip. Some downloads arrive with the wrong name. If Extract All refuses, check the actual file type in Properties.
It has a password and you do not have it. Then Windows cannot help, per the limitation above, and you need the password rather than a different program.
If Windows itself is failing to open things that should work, that is separate and is the service down or is it you has three tests that settle it quickly.
The command line one, for completeness
Microsoft also documents `tar` as included with Windows and handles .tar, .tar.gz, .zip and .7z from a terminal, without installing anything.
Ours, and marked as ours: worth knowing if you ever need to extract something on a machine where you cannot install software, or inside a script. Not something most people ever need.
Status: written 22 August 2026. Microsoft documents Windows 11 24H2 supporting ZIP, RAR, 7z and TAR natively, and warns that zipping encrypted files removes their encryption.
Do I need WinRAR or 7-Zip?
On Windows 11 version 24H2, usually not. You already have built-in support for ZIP, RAR, 7z and TAR, which Microsoft documents. The exception is password-protected archives, which Windows does not handle, so those still need a separate program.
Why is my zip file the same size as the files inside?
Because photos, videos and music are already compressed. Zipping them again saves almost nothing. Text, spreadsheets and documents shrink a great deal. A zip of holiday photos being barely smaller is normal.
Does zipping a file protect it?
No, and it can do the opposite. Microsoft warns that encrypted files added to a zipped folder "will be unencrypted when they're unzipped", so zipping protected documents to email them strips the protection off.
Why will my zip file not open?
Most often the download did not finish, which produces a corrupt or unexpected format error. Download it again first. After that, check it really is a zip in Properties, and check whether it needs a password Windows cannot handle.
The Short Version
- A zip holds several files as one and makes them smaller, losing nothing.
- Right-click, Extract All. Windows has needed no extra software for twenty years.
- Windows 11 24H2 now handles RAR and 7z too, so WinRAR is usually unnecessary.
- Password-protected archives are the exception and still need a separate program.
- Zipping an encrypted file removes its encryption. Microsoft says so explicitly.
- Photos and video barely shrink, because they are already compressed.
Where to Next
Check your Windows version in Settings, System, About before you install any archive program. On 24H2 you already have what you were about to download.
If your drive is short of space rather than your files being awkward, where your disk space went finds the big items, which are almost never your own documents.
And if a file will not open because the app itself is broken, is the service down or is it you settles that in two minutes.
If you hit an archive Windows could not open on a current version, tell me the format below. That list is worth keeping accurate.
Isaac Smith is the founder and editor of PC Glance, a website that covers computers, laptops, and technology. He is a tech enthusiast and a computer geek who loves to share his insights and help his readers make smart choices when buying tech gadgets or laptops. He is always curious and updated about the latest tech trends.