ZERO WIDTH NO-BREAK SPACE
U+FEFF
Block
Arabic Presentation Forms-B
Category
Format
UTF-8
0xEF 0xBB 0xBF
UTF-16
0xFF 0xFE 0xFF 0xFE
UTF-32
0xFF 0xFE 0x0 0x0 0xFF 0xFE 0x0 0x0
HTML

Python
u"\uFEFF"