In "The Great Gatsby," as Daisy and Gatsby renew their former love, their reunion in Nick's house and their afternoons spent in Gatsby's mansion, far from her husband, are part of the rising action. This plot element generates suspense about the resolution of the central conflict, leading to a climax.
No matter how simple or complex a story is, rising action is part of the plot. Even in a story as simple as "The Three Bears," rising action appears: in that tale, Goldilocks' progress from the bowls of porridge to the chairs and then to the beds of the bears constitutes rising action. With each series of impositions, her violation becomes more difficult to escape, moving from eating the baby bear's porridge to breaking his chair to sleeping in his bed. When the bears come home, even the series of questions that they ask continues to build the suspense, and so the rising action continues to the point where the bears find Goldilocks in bed, which is the tale's climax.
Rising action that builds to a climax is a necessary part of any successful story, as it maintains the reader's interest in the outcome of the events. After the climax, most stories also feature a trail of falling action that leads to the resolution.