What Does Byte Order Mark (BOM) Mean?

The byte order mark (BOM) is a piece of information used to signify that a text file employs Unicode encoding, while also communicating the text stream’s endianness. The BOM is not interpreted as a logical part of the text stream itself, but is rather an invisible indicator at its head. The byte order mark’s Unicode character is U+FEFF.

Techopedia Explains Byte Order Mark (BOM)

Unicode is a group of standards developed in the 1980s and ’90s in order to integrate all of the major computer languages into one coding lexicon. Unicode comes in several iterations, including UTF-8, UTF-16 and UTF-32 (which use 8, 16 and 32 bits per character, respectively).