In the Ubuntu file manager (usually Files (GNOME Files), also called Nautilus), Compress creates a single archive file containing the selected files and folders. It does not normally reduce the size of every file significantly, but it makes them easier to store, share, or back up.
Common archive formats include:
.zip – Best for sharing with Windows, macOS, and Linux users.
.tar.gz (or .tgz) – Common on Linux; combines files into a TAR archive and compresses it with Gzip.
.7z – Often gives better compression than ZIP, but requires compatible software to open.
For example, if you select a folder called RadioData and choose Compress, you might get:
RadioData.tar.gz
RadioData.7z
The original files remain unchanged; the compressed archive is created alongside them unless you choose a different location.
If your goal is to save disk space, compression helps most with text files, CSV files, logs, and source code. It usually has little effect on files that are already compressed, such as JPEG photos, MP3 music, MP4 videos, or PDFs.