Final answer:
The number of characters in a file name varies by operating system and file system, with a common maximum being 255 characters for modern systems like Windows with NTFS, and Unix-like systems.
Step-by-step explanation:
The number of characters that may be used in a file name depends on the operating system and the file system being used. For instance, in Windows with the NTFS file system, the maximum length for a file name is 255 characters, whereas on other file systems, such as older versions of FAT, the limit could be as low as 8.3, which means 8 characters for the name and 3 for the extension. On most Unix-like systems, including Linux and macOS, the limit is also typically 255 characters. However, it is important to note that these limits include the file path, so the actual file name length should be shorter to accommodate for the directory path.