A man's character may be learned from the adjectives which he habitually uses in conversation - Mark Twain
Adjectives are words that describe. While they are not integral to creating a sentence, they add colour and specificity to nouns. The adjectives that an author uses (or chooses not to use) are a major contributor to the style of the writing because they call attention to the author's (or character's) perception of the world, framing it through their eyes.
Let's look at adjectives in action. Take the following sentence:
A jack-o'-lantern sits on the ground.
This sentence gives the reader only the basic information. It tells them the subject (jack-o'-lantern) and what the subject is doing (sitting on the ground). Take a second to imagine the scene portrayed. What details have you added that are not included in the sentence? Without the use of adjectives, each person will come up with vastly different interpretations.
When adjectives are added, how does your interpretation of the scene change?
A jack-o'-lantern with a toothy grin sits on the ground.
A jack-o'-lantern with a cute smile sits on the ground.
A cheerful jack-o'-lantern sits on the ground.
A winsome jack-o'-lantern sits on the ground.
How do the different adjectives used change how you picture the jack-o'-lantern? Do you picture the same one for each sentence? Or does the change in adjective change what the jack-o'-lantern looks like?
Here is the image the above sentences are based on:
How close was what you imagined to this image? Did your image get closer when you were given sentences that included adjectives? This is the first thing to consider when using adjectives. How important is it that the reader's image of what you are describing matches your own?
Using adjectives to describe things helps to signal their importance. The more specific the description, the more it draws the reader's focus. Give the most detail to the characters, settings and things that play a large role in the narrative. Include adjectives that provide context to plot points and narrative events. Does it matter what colour dress the woman walking down the street is wearing? It might. Does the fact that it's purple mean your protagonist is reminded of a childhood friend? Does this mean they follow her? Or is the woman just there to add atmosphere to the scene and demonstrate that the protagonist isn't walking down an empty street?
The second thing to consider is the choice of adjective. The adjectives chosen by an author dictate the overall tone and impression that the reader takes away. Even very closely related words like cheerful and cheery give slightly different impressions that ripple through the text.
Consider the image of the jack-o'-lantern again. What other adjectives could be used to describe it? Childlike, smiling, cheerful, happy, cute, small, baby-faced, wide-eyed, orange, glowing, cartoon? Each one of these is an option and there are hundreds more that would also work. The one to choose depends on what you want to highlight. Think of the connotations an adjective gives and how it will affect the reader's perception of what you are describing.
Number of Adjectives
If you need three adjectives to describe something, then you've probably chosen the wrong something. - Roger Rosenblatt
There are some strong opinions out there about adjectives, with some authors vehemently opposed to their use believing that a strong noun eliminates the need for adjectives. While it is true that using a strong noun means adjectives usually aren't needed, adjective-light writing has a different feel to it than writing that uses lots of adjectives. Ultimately, the correct choice depends on the author's voice and the story they are trying to tell.
When using adjectives, it is important to use them strategically. Too many can bog a sentence down and make it difficult to understand.
She was wearing a knee-length, full-skirted, purple polka-dot dress; an oversized, pink hat with a wide brim, blue trim and white stars; and tall, black, thick-heeled pumps covered in rhinestones.
The description of this character's clothing is so detailed that by the time the reader reaches the end of the sentence, it's hard to remember what the sentence is about. In general, only one or two adjectives are necessary to describe an object. If you need more, as Rosenblatt said, you've probably chosen the wrong noun.
Shortening the sentence makes it easier to follow:
She was wearing a purple polka-dot dress, an oversized pink hat and black thick-heeled pumps.
This shortened version gives the reader a clear image of what the character is wearing without causing confusion. It also eliminates the need for semicolons, meaning less punctuation, which is usually easier for the reader to navigate. Depending on the voice of the author (and the importance of this character's clothes), the sentence could be further edited to have only a single adjective or no adjectives at all.
She was wearing a polka-dot dress, an oversized hat and thick-heeled pumps.
She was wearing a purple dress, pink hat and black pumps.
She was wearing a dress, hat and pumps.
While the first version of the sentence will almost universally be considered difficult to read, each edited option provides a different image to the reader. And each is valid. The "correct" version will depend on what elements are related to character development, atmosphere, plot and voice. The reader doesn't need to know everything that an author has in their head. Part of the fun of reading is that you get to make up some of the details on your own.
If you find you are consistently using more than two adjectives to describe a noun, then consider using a stronger noun or spreading the description over several sentences or paragraphs. Examine each adjective to determine if they are truly necessary. Focus on the details that are important. The look of clothing can tell the reader which kingdom a character belongs to. Hair texture or skin colour can designate the race of a character. The feeling of an object can differentiate different dimensions or states of being. Use adjectives to add information that broadens the reader's understanding of the characters and world you are building. If the adjective isn't serving the narrative, then it isn't needed.
The Royal Order of Adjectives
The final piece of the adjective puzzle is the order they are written in. If you are a native English speaker, this is likely something that you have never thought about. But if you've ever heard someone list adjectives and thought "That sounds wrong" the royal order of adjectives is most likely why.
Adjectives must be listed based on the following order:
Determiner (articles and other limiters such as possessive pronouns)
Quantity
Observation or opinion
Size
Age
Shape
Colour
Origin
Material
Qualifier (adjective that is part of the noun)
This is why
A small ancient blue book.
sounds correct, but
A blue ancient small book.
sounds off.
The second option sounds jarring because it does not adhere to the royal order of adjectives. However, the royal order doesn't stop a sentence from feeling bloated and confusing if there are too many adjectives.
The five ugly, huge, old, curved, grey, English leather wingback chairs...
Grammatically, there is nothing wrong with this phrase, but the description is so long that by the time the noun has arrived, it's difficult to remember anything that came before.
Exactly why this order prevails is unclear, but it is likely a combination of convention and importance. As we get closer to the noun, the adjectives become more integral to the essence of the noun. By the time we have reached the qualifier, the adjective has almost become a part of the noun. In the example above, the wingback that precedes chair gives the most important information about the type of chair. Most people will picture similar chairs when they hear wingback chair or rocking chair in a way that they won't with grey chair or ugly chair.
So if the adjectives aren't sounding quite right, check their order. If the royal order is correct, then examine the adjectives themselves. Are there too many? Would a synonym make the words flow better? Are they all necessary? Are they adding context or just filling space?
In Conclusion
Adjectives are an important tool in the writing toolbox that when used thoughtfully and correctly can help bring fictional worlds and characters to life. Understanding their uses is an important part of writing well, whether you choose to use them or not.