Main Japanese article: 感嘆符.
The exclamation point or mark (感嘆符 kantanfu) is usually used after an interjection or exclamation to indicate strong feelings or high volume, and generally marks the end of a sentence. A sentence ending in an exclamation mark is either an actual exclamation ("Wow!", "Boo!"), a command ("Stop!"), or is intended to be astonishing in some way ("They were the footprints of a gigantic hound!").
While there is no exclamation point in Japanese, it is very commonly used, especially in casual writing, fiction and manga.