Conjugation is the creation of derived forms of a verb from one basic form. Conjugation may be affected by person, number, gender, tense, mood, voice, or some other language-specific factor or factors. When a verb is used to function as the action done by a subject, the verb must be conjugated in most languages.
For example, here's a sample conjugation of the English verb to be and its Latin and French equivalents, esse and être.
|Form / Person||English||Latin||French|
|1st singular||I am||sum||je suis|
|2nd singular||you are||es||tu es|
|3rd singular||he, she, or it is||est||il/elle est|
|1st plural||we are||sumus||nous sommes|
|2nd plural||you are||estis||vous êtes|
|3rd plural||they are||sunt||ils/elles sont|
Note that the similarity between English is and Latin est is not a mere coincidence, but rather one of the consequences of them having a distant common ancestor (see Indo-European languages). French is a derivative of Latin, which explains the much greater similarity in the way their conjugate this verb.
See also /Declension