The Japanese expression かもしれない functions like a single unit to express possibility. However, it's actually formed from the particle かも, the potential form of the う-Verb 知(し)る (to know), and the negative auxiliary verb ない. While typically translated as 'might' or 'maybe', a more direct interpretation would be something like 'one cannot know if (A) is the case'.

To express uncertainty, かもしれない can be appended directly to the plain form of any verb, noun, な-Adjective or い-Adjective.

• 午後(ごご)から雨(あめ)が降(ふ)るかもしれない。
  It might rain this afternoon.
• その話(はなし)は嘘(うそ)かもしれない。
  That story might be a lie.
• 田中(たなか)さんはこの映画(えいが)が好(す)きかもしれない。
  Tanaka-san might like this movie.
• その道(みち)は危(あぶ)ないかもしれないから、別(べつ)のルートで行(い)こうよ。
  That road might be dangerous, so let's take a different route.

Because this grammar pattern includes the う-Verb 知(し)る, it can be conjugated into its polite potential form. This changes かもしれない to the more formal かもしれません.

• 会議(かいぎ)はもうすぐ終(お)わるかもしれません。
  The meeting might be over soon.

Since かもしれない is used so often in everyday conversation to show uncertainty, a few casual variations have become common. The most frequent are かも, かもしらん, and かもしれん.

• ちょっと疲(つか)れたから、今日(きょう)は早(はや)く寝(ね)るかも。
  I'm a little tired, so I might go to bed early today.
• あいつ、昨日(きのう)の約束(やくそく)を忘(わす)れていたかもしらん。
  That guy might've forgotten about our promise yesterday.
• 彼(かれ)は忙(いそが)しいから、パーティーには来(こ)ないかもしれん。
  He's busy, so he probably won't come to the party.

Of these shortened structures, かも is overwhelmingly the most frequently used. Be aware that かもしらん can carry a slightly coarse or masculine nuance.