Sometimes a sign looks like the object or action it represents, but this is not always true. For many signs, a person just has to learn the meaning, like words in a spoken language. It's not easy to guess the meaning from what the sign looks like. This is another thing that makes sign languages different from mime; in mime, the meaning of a gesture is obvious, it doesn't have to be learned. However, signs aren't totally arbitrary either. Once a person knows the meaning of a sign, the form of the sign can often help remember the meaning.