Fill in the Blanks GIT basicsOnline version Actividad de prueba. by Guillermo Abadía Cenoz 1 file checksum check information SHA summed corruption hexadecimal hash Everything in Git is - before it is stored and is then referred to by that . This means it's impossible to change the contents of any file or directory without Git knowing about it . This functionality is built into Git at the lowest levels and is integral to its philosophy . You can't lose in transit or get without Git being able to detect it . The mechanism that Git uses for this checksumming is called a - 1 . This is a 40 - character string composed of characters ( 0 ? 9 and a ? f ) and calculated based on the contents of a file or directory structure in Git .