How is utf-8 different from utf-8 with BOM?

Question

HTML

I saved the html page in utf-8, when I opened it in Chrome, I got cracks, then I saved it in utf-8 with BOM, everything is fine.
Please explain the difference between
PS encodings, Cyrillic was used

Answer 1

Here I ask .

Answer 2

Apparently, the encoding is not specified in the HTML page itself (via <meta http-equiv="content-type" content="text/html; charset=utf-8">), and auto-detection in Chrome does not work as it should (or it is configured ). The presence of a BOM marker at the beginning of the file clearly indicates the use of one or another variety of Unicode.