This article explains how to zip and unzip a file on a Chromebook using built-in ChromeOS tools. Using zip files is a popular way to compress multiple files into one smaller package.
Zipping and Unzipping Files on a Chromebook
Zipping and unzipping files is done in the Files app, a built-in app in ChromeOS.
Open your app launcher and click on Files.
Use the left sidebar to find the files you want to zip. Check the circle for each file.