In some cases, letters are used as "in-line diacritics", with the same function as ancillary glyphs, in that they modify the sound of the letter preceding them, as in the case of the "h" in the English pronunciation of "sh" and "th".The tilde, dot, comma, titlo, apostrophe, bar, and colon are sometimes diacritical marks, but also have other uses.Examples are the diaereses in the borrowed French words naïve and Noël, which show that the vowel with the diaeresis mark is pronounced separately from the preceding vowel; the acute and grave accents, which can indicate that a final vowel is to be pronounced, as in saké and poetic breathèd; and the cedilla under the "c" in the borrowed French word façade, which shows it is pronounced .In Gaelic type, a dot over a consonant indicates lenition of the consonant in question.Diacritical marks may appear above or below a letter, or in some other position such as within the letter or between two letters.The main use of diacritical marks in the Latin script is to change the sound-values of the letters to which they are added.
Languages that treat accented letters as variants of the underlying letter usually alphabetize words with such symbols immediately after similar unmarked words. in phone books or in author catalogues in libraries), umlauts are often treated as combinations of the vowel with a suffixed e; Austrian phone books now treat characters with umlauts as separate letters (immediately following the underlying vowel).
The j, originally a variant of i, inherited the tittle.
The shape of the diacritic developed from initially resembling today's acute accent to a long flourish by the 15th century.
Diacritic is primarily an adjective, though sometimes used as a noun, whereas diacritical is only ever an adjective.
Some diacritical marks, such as the acute ( ´ ) and grave ( ` ), are often called accents.