Learn French: Il est possible que le client préfère ce produit. - It is possible that the client prefers this product.

In French, the subjunctive is used to express uncertainty, doubt, or subjectivity. Il est possible que (it is possible that) introduces uncertainty because we aren't sure if the client actually prefers the product or not.

préfère looks exactly like the normal present tense. How do we know it is in the subjunctive here?

For -er verbs like préférer, the subjunctive forms for je, tu, il/elle/on, and ils/elles are spelled exactly the same as the present indicative (the normal present tense). We know it is the subjunctive here strictly because of the trigger phrase Il est possible que.

If I wanted to say "It is probable that...", would I still use the subjunctive?

Surprisingly, no! French makes a distinction here. Il est probable que (it is probable that) is considered certain enough to take the normal present tense (the indicative). However, il est possible que introduces enough doubt to require the subjunctive.

Just as a refresher, why do we use ce for "this" instead of cet or cette?