End Of File or EOF is a specific designation for a file marker that indicates the end of a file or data set.
Techopedia explains End Of File (EOF)
Along with another tag Beginning Of File or BOF, End Of File delineates the boundary of some data set that is being operated on by a computer. For example, a loop or iterative program that is going along analyzing text at the end of a text file can recognize an EOF tag and stop performing operations when the end of the file is reached.
The BOF and EOF markers represent some very simple syntax that was used for even the most primitive computing systems in the early days of programming. These types of tags and markers promote the idea of looking at code as a straightforward translation from machine language to a linear, accessible programming language.
As mentioned above, one of the problems that EOF helps to solve involves open-ended read/write or read operations. A linear program without an EOF marker may try to read past what’s in the file, returning one of a number of errors. To prevent this, a code loop can check for EOF with each iteration, to make sure that the execution ends at the end of the file, regardless of its length.