The Spiral Model, defined by Barry Boehm in 1986, integrates iterative prototyping with sequential development, emphasizing risk analysis and customer feedback throughout its phases: planning, risk analysis, engineering, and evaluation. It is particularly beneficial for medium and large-scale software projects with uncertain requirements and complexity, allowing for extensive use of prototypes and better risk management. However, the model also has drawbacks, including increased management complexity, excessive documentation, and potentially indefinite iteration timelines.