How to ZIP Files and Folders, and Why It Helps When Emailing
Learn what a ZIP file is, how to zip and unzip files and folders, when zipping helps with email and uploads, and the mistakes to avoid when sharing ZIP files.
2 November 2026 3 min read
What a ZIP file is
A ZIP file is a single file that contains one or more other files or folders inside it. You can think of it as a packed envelope. The person who receives it opens, or extracts, the envelope to get back the original files with their names and folder structure intact.
ZIP is supported on Windows, macOS, Android and most other systems without installing special software, which is why it is the most common archive format for sharing. Other formats such as RAR and 7z exist, but ZIP is the safest choice when you do not know what the receiver uses.
Why zipping helps
The biggest benefit is convenience. Instead of attaching 25 separate scanned pages to an email, you attach one file. The receiver downloads one item and gets everything in the right folders.
ZIP can also make some files smaller. Text files, Word documents saved in older formats, spreadsheets in CSV and code files often compress well. However, files that are already compressed, such as JPG photos, MP4 videos and most PDFs, usually shrink very little. Zipping them is still useful for bundling, but do not expect a big size reduction.
- Send many files as one attachment
- Keep folder structure intact, for example a project with subfolders
- Upload multiple documents where a portal accepts only one file
- Reduce size for text-heavy files
How to create a ZIP file
On Windows, you can select files, right-click and choose the option to compress to a ZIP file. On macOS, right-click and choose Compress. On a phone or any device with a browser, you can use Filyzo's Files to ZIP tool, which builds the ZIP inside your browser without uploading your files.
- Put all the files you want to send into one folder.
- Give the files clear names before zipping.
- Select the files or folder and create the ZIP.
- Name the ZIP clearly, for example project_report_team4.zip.
- Open the ZIP once to check that everything is inside.
How to unzip a file
When you receive a ZIP, extract it before working on the files. Opening a document directly from inside the ZIP sometimes opens a temporary copy, and your changes may not be saved where you expect.
On most computers, double-click or right-click and choose Extract All. Filyzo's Unzip Files tool lets you open a ZIP in the browser and download individual files, which is handy on a phone or a shared computer.
Email and upload limits
Email services set a limit on the total size of attachments, and the limit differs between providers. If your ZIP is too large, you can split the content into two or three smaller ZIPs, reduce image sizes first, or share through a cloud storage link instead.
Some organisations block ZIP attachments or scan them strictly, because ZIP files are sometimes used to hide harmful software. If a recipient says they did not get your mail, ask whether ZIP attachments are allowed.
Safety tips and common mistakes
Treat ZIP files from unknown senders with caution. Do not open files inside them that end in .exe, .bat, .js or similar unless you trust the source completely. A file named invoice.pdf.exe is not a PDF.
Common mistakes include zipping the wrong folder, sending a ZIP that contains other people's private files by accident, and forgetting that ZIP alone does not protect sensitive data. If you share confidential documents, use a secure method approved by your college or organisation.