Homoglyphs are similar or identical -looking characters. Their identification is particularly difficult when it can not be inferred from the context, such as in certain ratios.

Thus, the letter O and the number 0, as are the letters I and l often confused with each other. Could homoglyphs even when using different alphabets occur. A Latin H, Cyrillic Н and Greek Η are difficult to distinguish from each other.

Mehrbuchstabige Homoglyphe may arise if several individual letters are visually perceived as a single letter: rn than m, cl than d, or vv w as, and sometimes fi as A.

Homoglyphe are a particular problem for text-processing programs.