An "aside" is a dramatic device in which a character speaks to the audience. By convention the audience is to realize that the character's speech is unheard by the other characters on stage. It may be addressed to the audience expressly (in character or out) or represent an unspoken thought. An aside is usually a brief comment, rather than a speech, such as a monologue or soliloquy. Unlike a public announcement, it occurs within the context of the play. An aside is, by convention, a true statement of a character's thought; a character may be mistaken in an aside, but may not be dishonest.
Aside is used to gossip about characters or other characters without their consciousness, give audiences better understanding of matters, as well as make audiences laugh; this humour that may be generated is because the character or characters being talked about is or are not conscious of the fact they being spoken of.