Circumflex in French

The circumflex (ˆ) is one of the five diacritics used in French orthography. It may appear on the vowels a, e, i, o, and u, for example â in pâté.

The circumflex, called accent circonflexe, has three primary functions in French:

• It affects the pronunciation of a, e, and o. Although it is used on i and u as well, it does not affect their pronunciation.
• It often indicates the historical presence of a letter, commonly s, that has become silent and fallen away in orthography over the course of linguistic evolution.
• It is used, less frequently, to distinguish between two homophones. For example, sur ('on/about') versus sûr '(sure/safe'), and du ('of the') versus dû ('due')

And in certain words, it is simply an orthographic convention.