As character names:

U+FFFD REPLACEMENT CHARACTER character (�)

As raw characters:

�

As a string of HTML entities:

�

Decoder output:

Byte number 1 is decimal 240, hex 0xF0, octal \360, binary 11110000
This is the first byte of a 4 byte sequence.

Byte number 2 is decimal 143, hex 0x8F, octal \217, binary 10001111
This is continuation byte 1, expecting 2 more.

Byte number 3 is decimal 191, hex 0xBF, octal \277, binary 10111111
This is continuation byte 2, expecting 1 more.

Byte number 4 is decimal 189, hex 0xBD, octal \275, binary 10111101
This is continuation byte 3, expecting 0 more.

U+FFFD	REPLACEMENT CHARACTER
	* used to replace an incoming character whose value is unknown or unrepresentable in Unicode
	* compare the use of 001A as a control character to indicate the substitute function
	x (uncertainty sign - 2BD1)
	x (negative squared question mark - 1FBC4)