The ability to compress a file or a group of files so that they take up less space is something that has been available for practically as long as consumer computers have been available. The most popular method is called ZIP, which was first introduced back in 1989 and is still being used (although there are others just as, or more, efficient, such as RAR and TAR).

Once upon a time, you would have had to use a third-party app in order to zip or unzip files. However, that ability is now built into most, if not all, operating systems.

Zipped files are very easily identified — just look for the .zip at the end of the file name. If you want a slightly more complete explanation of the method for zipping a file (and this is still actually a very simplistic way of describing it), it removes redundant data — data that is repeated within the files so that the file can be made much smaller in a process known as lossless data compression. That data is then replaced when the file is reconstituted.

In this article, we explain how to zip and unzip standard ZIP files in the five most popular operating systems: macOS, iOS, Windows, Android, and ChromeOS.

• Select your desired files from your Finder listing using either Shift-click (to choose a single group of files) or Command-click (to select several files separately).
• Right-click anywhere on the highlight and select Compress.
• You’ll now have a zip file containing those files. (The original files will still be there.) The new zip file will be titled Archive.zip; you can rename it anything you want (while, of course, leaving the zip designation alone).

• You can unzip a file directly from your Finder window.
• Find the file and double-click on it. (Or right-click and choose Open.) You may see a window pop up that says “expanding” depending on how big the zipped file is and how fast your computer is.
• You’ll then see a new folder with the same name as the zipped file. Click on that folder to find all of the files that were contained within the zip file.

• Open your Files app and find the files (or folder) that you want to zip.
• If you want to compress more than one file, select the menu icon (three dots) in the top-right corner, tap on Select, and then tap on the files you want to compress. If you only want to compress one file, you just have to long-press on that file.
• Select the three-dot icon in the lower-right corner and select Compress.
• You’ll now have a compressed file (probably named Archive.zip) sitting among your previous files.

• Find the zip file you want to uncompress, and tap it.
• You’ll now have a new folder with the same name as the zipped file. Tap on the folder to see your uncompressed files.

• Open File Explorer and select the files or folders that you want to compress by either highlighting a group of them using Shift-click, highlighting individual files using Ctrl-click, or clicking the checkboxes to the left of each file name.
• Once you’ve chosen your files, right-click on the highlighted area and select Compress to ZIP file.
• You’ll find a new compressed folder in File Explorer named after one of the included files. You can rename the folder anything you wish.

To open one of a group of compressed files:

• In File Explorer, double-click on the compressed folder to open it.
• Double-click on the file you want, and it will open in the associated app.

To extract all the files in a compressed folder:

• In File Explorer, click on the checkbox next to the compressed folder listing and then on the Extract all button that will appear at the top of the page.
• A pop-up window will then allow you to select a destination for your files. (Click on the Browse button if the destination shown is not the one you want.)
• Click on the Extract button.

Unfortunately, it is difficult to zip up a file using an Android phone unless you have an app that will help you do it. There are several good ones in the Play Store, including ZArchiver, WinZip (one of the oldest zip-related apps out there), and RAR (which will compress your files using a variety of protocols, including ZIP and RAR, among others).

If you have a Samsung phone, however, you have another option for zipping files besides using a third-party app:

• To zip several files, go to My Files, and select the files you want to zip.
• Select the three More dots at the bottom right, and then tap on Compress.
• Type in a name for your compressed file, check Protect with password if that’s what you want to do, and select Compress.

You can unzip a zipped file using the Files by Google app that comes included with many Android phones. (If your phone doesn’t come with the app, you can download it from the Play Store.)

• In the Files app, select Browse from the bottom menu, and then tap on the search icon in the top-right corner.
• The easiest way to find your zipped file (if you don’t remember the exact file name) is simply to type “zip” in the search field at the top.
• Tap on the file you want to unzip.
• You will be asked if you want to extract the file or files and shown which type of files they are (such as Images or Documents). Tap on the Extract button.
• Another pop-up window will inform you that the files are extracted and repeat their file types. There is also a checkbox in case you want to delete the original zip file. When you’re ready, tap Done.

If you’re using a Samsung phone, you can also use the My Files app:

• In My Files, tap on the file you want to extract.
• Select the three-dot More icon, and then choose either Extract or Extract to current folder.

• You can compress files in the Files app. Find it by clicking on the app launcher on the left side of your shelf. Then go to the folder your files are in (files are listed on the left).
• You can select individual files by clicking in the circles next to each file name. You can also pick a group of files by clicking on the first and then using Shift-click to select the last.
• Right-click on any of the selected files, and choose Zip selection from the drop-down menu.
• The files will be compressed into a file named Archive.zip and will appear in your current folder. To rename the file, right-click on it and select Rename.

Unzipping a file on a Chromebook was once a pain, demanding that you copy each file you wanted from the compressed file and then paste it in another folder. However, in more recent versions of ChromeOS (version 102 and later), the process is a lot easier.

• Right-click on the zipped file that you want to open.
• Click on the menu selection Extract all.
• The uncompressed file will appear in your Downloads folder as a new folder with the name of the zipped file and will contain all of the uncompressed files. For example, if the name of the zipped file was Archive.zip, you will now have a new folder in Downloads called Archive.