Sharing large files can be difficult, especially as many email services have a limit on how large a file or group of attachments can be. You can of course use services such as WeTransfer to move documents and folders around the web, but it's far simpler to create a zip file that compresses the size down to a more manageable amount.
The good news is that macOS has a built-in feature for creating zip files, and here's how to use it.
How to create a zip file in macOS
To create your zip file, find the file or folder that you want to compress. Control-click or use the two-finger tap gesture on your trackpad to bring up the contextual menu. From here select the Compress “[File Name]” option, which will create a zip file that uses the same filename except with .zip at the end. If you're compressing a folder then macOS will give it the name Archive.zip instead.
What to do if the Compress option doesn’t work on macOS
If you don't see the Compress option or it doesn't create a zip file when selected, then there could be an issue with the permissions on that particular file or folder. To check, launch Finder then select File > Get Info or alternatively, hold down the Command key and press i.
Click on the Sharing & Permissions section to open it up and show more details.
This will reveal a list of all the users who can access the file, so check for your name and see what permissions are displayed in the right-hand column entitled Privilege.
Ideally you want the Read & Write permissions as this allows you to make adjustments to the file. If your permissions say Read Only try clicking on the words to open up the menu where you can select the Read & Write option.
If you're not logged in as an administrator you may need to click the padlock icon, enter the administrator name and password, then change the setting to Read & Write. With this done you should now be able to use the Compress option on the file or folder.
How to unzip a file on macOS
Of course, once you've created a zip file you'll also want to be able to unzip it. Thankfully this is easy in macOS as all you have to do is double-click the file and the operating system automatically uses the unzip function.