IRREGULAR ‘CER’ VERB

Verbs that end in -cer in the infinitive form change c to ç when in front of the vowels a, o or u in order to keep the s sound in the infinitive form and retain its identity. That little mark under the c (ç) is called une cédille.

Some common verbs that end in -cer in the infinitive form are:
annoncer / to announce
avancer / to advance
commencer / to begin, to start
divorcer / to divorce
effacer / to erase, to efface
lancer / to launch, to hurl
menacer / to threaten
placer / to place, to set
prononcer / to pronounce
remplacer / to replace