Very often when I've written a poem and posted it to my portfolio (you can view my portfolio by clicking the link in the upper right hand section on this site), I will hear, "your poem made me cry," or, "you know you really got me angry with this poem",
If I have made tears well up or anger surface I have done my job.
Writers seek constantly to affect their readers. That is why we write. Some prefer shock value, some comedy and others, like myself emotional responses.
Words, after all are our primary form of self expression. All of us tell tales and stories, relate experiences and observations. Some of us raise emotions with our words ie: Salmon Rushdie who angered a whole nation with his book, Satanic Verses.
To cause someone to feel what you feel as you write makes the reader more apt to return to you for another book or story. Whether it is happiness, sadness, fear or longing, a reader wants to experience what the writer is trying to get across. Even though the emotion in the story may not be earth shaking, the feelings that the characters are experiencing gives way to involvement in the story and that is what every author wants.
Think about trying to tell someone of a wedding you attended. Think of how happy the couple was, or how the parents cried with pride. Consider the wedding reception where everyone was joyous and partied to congratulate the bride and groom. How would you tell about it? Would you highlight the overpowering joy? Or, the way they looked at one another? Both of these things would heighten the emotional content of your story and add that little bit that makes a good story a great one.
That brings up the color of words.
Yes, words have color. Let's use the word misty. When you think of mist, you may see white, grey or even a pale blue in your mind's eye. Or, bright. We see white, blaring yellow, pale, pearl grey; these words while not specifically blue or red, are conducive to color. They set a mood; one that can be used to great advantage.
Our English language is rich in description. It is a value to any genre of writing. Take a few moments while writing to consider what your words portray and how you want to use them.