Verify an Ubuntu installation image
Use the lesson's text route if these host commands are unfamiliar.
No image, checksum or observed command result is supplied here.

For the x86-64 route, use Ubuntu 24.04 LTS Desktop amd64 media:
https://releases.ubuntu.com/24.04/
Check the complete filename and release before downloading.
Use SHA256SUMS and SHA256SUMS.gpg for that same release.
Do not use a checksum belonging to another filename or point release.

A checksum describes file bytes. SHA-256 produces 64 hexadecimal digits.
A digital signature helps establish who published the checksum file.
Follow Canonical's signature and key-fingerprint instructions:
https://ubuntu.com/tutorials/how-to-verify-ubuntu
If you cannot complete them, defer installation and use the text case.

Hash commands (read the lesson's explanation first):
Replace ISO-FILENAME.iso with the exact full path to your downloaded ISO.
Keep the straight quotes around the path, including any spaces.
Choose ONLY the line for your host's command window.

Windows PowerShell:
Get-FileHash -Algorithm SHA256 -LiteralPath 'ISO-FILENAME.iso'
Linux terminal:
sha256sum 'ISO-FILENAME.iso'
macOS Terminal:
shasum -a 256 'ISO-FILENAME.iso'

Compare all 64 digits with the SHA256SUMS line for that exact image.
Hexadecimal letter case does not change the value.
Mismatch: stop; check filename, release and download completeness.
Match: the file agrees with that checksum. This alone does not establish
publisher identity or guarantee software free of harmful behavior.
Record what you checked; do not mark an unchecked image verified.