Digital forensics is a branch of the forensic sciences related to the investigation of digital devices and media. Within the field a number of "normal" forensics words are re-purposed, and new specialist terms have evolved.
The unused space at the end of a file in a file system that uses fixed size clusters (so if the file is smaller than the fixed block size then the unused space is simply left). Often contains deleted information from previous uses of the block
Steganography
The word steganography comes from the Greek name “steganos” (hidden or secret) and “graphy” (writing or drawing) and literally means hidden writing. Steganography uses techniques to communicate information in a way that is
hidden.[4]