The evolution of 5G is anticipated to support a broad spectrum of mobile and multimedia services, such as 5G-based telecommunications, high-speed internet, evolving mobile access, autonomous vehicles, and smart inspection by unmanned aerial vehicles. These services introduce novel issues for wireless networks, demanding ultra-low latency, ultra-high data rates, and extensive connectivity. This drives the evolution of RAN towards next-generation technologies. Traditional RANs are based on a distributed RAN (D-RAN) model, where all RAN functions are statically integrated into a limited number of elements. However, this integrated architecture struggles to support the advanced technologies and services required for various emerging use cases. To address these limitations, 5G introduces a new RAN system architecture known as disaggregated RAN. This approach separates the monolithic network functions into distinct components that are capable of being relocated individually without affecting their ability to collaborate and provide comprehensive network services. This chapter explores the evolution of wireless networks and their technological advancements.