Manual decoding means interpreting an encoded pattern without relying on a scanner to read it automatically. For a QR code, this involves examining its grid and understanding how its structure represents data. Because QR codes include formatting and error-correction information as well as payload data, doing this by hand can be difficult and error-prone.
In cyber security, the useful lesson is to inspect what a code contains, not to assume its appearance reveals its purpose. A QR code may encode a link or contact details; checking the decoded payload before opening or using it can help avoid acting on an unexpected destination. Manual decoding is an alternative way to examine the data, not a guarantee that it is safe or a routine substitute for a scanner.