Human beings have always been driven to explain the unknown, remember their history and express their emotions through artistic uses of language. Storytelling, poetry, song and drama are the vehicles by which every human experience has been captured and honored. One of the most powerful of the literary devices creates a visual picture to help express some kind of meaning. There are many types of imagery that are used literarily, including simile, metaphor and synecdoche.
At its simplest, the term "imagery" simply means a group of words that create a mental picture. Writers know that a picture truly is worth a thousand words in the minds of readers, so thy attempt to combine vivid or unexpected verbs and specific nouns that will force readers to visualize rather than intellectualize. Personifying is one way that this is accomplished. A writer who refers to a house on the block has provided information but not a picture. A writer who refers to a dilapidated, gray house squatting on a treeless lot has simultaneously created an image and suggested human traits.
Among the types of imagery that school children are taught, the first is simile. Most adults remember being drilled in the definition: a simile is the comparison of two unlike things using "like" or "as." It’s a functional definition, but it misses the heart of the matter. Simile finds the same sense of being within two things that, on the surface, seem to share nothing in common. It is natural to even a young child, who might, for example, describe a garden hose as being like a water snake.
Another one of the types of imagery is the use of metaphor. Like simile, metaphor finds identification between two unlike things, but it merges them into a single entity, creating a single image that reflects qualities of both things. This type of image, too, is natural to children who delight in finding connections between things that bear little in common. A child who says “I’m eating a tree” while nibbling on a stalk of broccoli is choosing metaphor from the types of imagery to describe what is happening.
Synecdoche is another type of imagistic literary device. It is almost like a literary nickname, not for a person but for a thing. Synechdoche is the name given when a larger thing or idea is implied by the naming of a smaller piece of the whole. Through use and over time, synecdochic expressions can become idiomatic expressions that are used almost to the exclusion of the original name for the whole.
An example of this is the replacement of the term "worker" by the word "hand." A farmer might mention he’s just hired a new hand, and a ship’s captain will shout “All hands on deck!” when the seas become rough. Parts-for-whole substitution is also common for objects. A sail represents a ship, and a crown represents a king, for example.