Dotted and dotless I

The Turkish alphabet, which is a variant of the Latin alphabet, includes two distinct versions of the letter I, one dotted and the other dotless.

The dotless I, I ı, denotes the close back unrounded vowel sound (/ɯ/). Neither the upper nor the lower case version has a dot.

The dotted I, İ i, denotes the close front unrounded vowel sound (/i/). Both the upper and lower case versions have a dot.

Examples:

In contrast, the letter j does not have this distinction, with a dot only on the lower case character: J j.

In scholarly writing on Turkic languages, ï is sometimes used for /ɯ/.

Consequence for ligatures

In some fonts, if the lowercase letters "fi" are placed adjacently, the dot-like upper end of the "f" would fall inconveniently close to the dot of the "i", and therefore a ligature glyph is provided with the top of the "f" extended to serve as the dot of the "i". A similar ligature for "ffi" is also possible. Since the unligatured forms are unattractive and the ligatures make the "i" dotless, such fonts are not appropriate for use in a Turkish setting. However, the fi ligatures of some fonts do not merge the letters and instead space them next to each other, with the dot on the i remaining. Such fonts are appropriate for Turkish, but the writer must be careful to be consistent in the use of ligatures.