You cannot extract a single part independently if it is a truly split archive; you need (part1, part2, etc.) to successfully rebuild the original file.
Many email services have strict attachment size limits (e.g., 20MB-25MB). Splitting a large file allows it to be sent across multiple emails. Download File part1.zip
High-capacity files, such as operating system images or large software packages, are split so that if a download fails midway, you only need to re-download the affected part rather than the entire multi-gigabyte archive. You cannot extract a single part independently if