What is a file signature?

A file signature is a unique identifier for a file based on its content, and this is why the chosen answer is accurate. File signatures, also known as magic numbers, are typically found in the header of a file and consist of a specific sequence of bytes that indicates the format of the file. This allows forensic examiners and software applications to correctly identify the type of data stored within a file, regardless of its name or extension.

For instance, an executable file may start with a particular byte sequence that differentiates it from other file types, even if the file is incorrectly named. This capability is critical in digital forensics, where accurate identification of file types can be essential for analysis, investigation, and evidence collection.

The other options do not accurately describe what a file signature is. A file's name does not necessarily reveal its content or type, as it can be renamed arbitrarily. The creation date of a file provides information about when the file was made, but it does not indicate the file's content or format. Similarly, a description of the file's purpose can be subjective and varies from user to user, lacking the specificity and consistency that file signatures offer.