Network scalability refers to the ability of a network to handle an increasing amount of work or to accommodate growth without compromising performance. This means that as more devices, users, or data are added, the network can expand efficiently, ensuring that speed and reliability remain intact. There are two main types of scalability: vertical and horizontal. Vertical scalability involves upgrading existing hardware to improve performance, while horizontal scalability adds more devices or nodes to the network. Both approaches help maintain optimal functionality as demand increases, making scalability a crucial aspect of modern network design.