Final answer:
An end-of-file marker is used to indicate the end of data in a file, similar to how punctuation marks the end of a sentence in English.
Step-by-step explanation:
In many computer systems, a special set of characters known as an end-of-file marker is written at the end of a file. This marker is used by the system to indicate that there are no more data to read from the file. It's similar to how a period ends sentences in English grammar, signaling the conclusion of a statement. Files have a size, just like how you can measure the weight of a physical folder filled with papers. In electronic file systems, the directory can tell you the exact size of each file, which is analogous to counting papers or adding up numbers to know the contents of a physical folder.