Homoglyph

In orthography and typography, a homoglyph is one of two or more graphemes, characters, or glyphs with shapes that appear identical or very similar but may have differing meaning.

Virtually every example of a homoglyphic pair of characters can potentially be differentiated graphically with clearly distinguishable glyphs and separate code points, but this is not always done.

Typefaces that do not emphatically distinguish the one/el and zero/oh homoglyphs are considered unsuitable for writing formulas, URLs, source code, IDs and other text where characters cannot always be differentiated without context.

Allographs are typeface design variants that look different but mean the same thing – for example ⟨g⟩ and ⟨g⟩, or a dollar sign with one or two strokes.

In the days of early mechanical typewriters these were typed with the same key (using the "backspace and over-type" technique), which was also used for a double inverted comma.

In the early days of mechanical typewriters there was very little or no visual difference between these glyphs, and typists treated them interchangeably as keyboarding shortcuts.

Early English typesetters imported Dutch typesets that did not contain the latter character, so used the letter ⟨y⟩ instead because (in Blackletter typeface) they look sufficiently similar.

[7] Employing advanced security solutions, particularly those capable of scanning for homoglyph variations in domain names, can automate the detection and prevention of potential threats.

Additionally, implementing stringent domain name monitoring and registration policies can help identify and neutralize homoglyph-related risks promptly.

By fostering a culture of cyber vigilance and leveraging cutting-edge technologies, organizations can fortify their defenses against homoglyph attacks, ensuring a more secure online environment.

[1] These present security risks in a variety of situations (addressed in UTR#36)[8] and were called to particular attention in regard to internationalized domain names.