In Alice Walker's The Color Purple, the title of the novel, as well as the color purple itself, have symbolic significance.
The color purple symbolizes elegance, royalty, freedom, and all that is good in the world. In letter 12, Celie shops for a purple dress, but the store does not have any purple dresses, so she has to settle for a blue one instead. Blue is a color often associated with sadness, such as in the expression "feeling blue."
Celie longs for the independence, liberation, and elegance symbolized by the color purple, but for the time being, she must settle for sadness and hardship, which is represented by the color blue.
Later in the novel, Shug tells Celie that God wants people to enjoy their lives, and they (God is gender neutral in the book) create simple pleasures, such as the color purple, for humans to notice and delight in.
The novel's title is a reminder to "stop and smell the roses," as the well-known expression says. In other words, it is a reminder to notice, appreciate, and enjoy the small, simple pleasures in life.
Shug tells Celie that God is angered when people walk past the color purple and do not take notice of it. Shug teaches Celie that enjoying her life is a way of honoring God because God wants people to enjoy their lives.
By the end of the novel, Celie learns to enjoy and appreciate her life. She has her own house and fills her bedroom with red and purple decorations. She has finally attained the elegance and freedom associated with the color purple, even if not in the way she expected.