GraphQL is a query language and runtime for APIs that helps to deliver data from a server to a client, allowing users to request specific pieces of data and fetch exactly it. It provides the opportunity to get all the data from several sources through one request, favorably affecting website performance. GraphQL is also a data source-independent system, which means it doesn't matter where the data is stored. This technology is particularly useful for building progressive web apps (PWAs) in Magento 2, as it speeds up data delivery and reduces server queries. However, there are some drawbacks to using GraphQL in Magento 2, such as the lack of ready-made options and its inability to replace REST API entirely for complex projects. Nevertheless, GraphQL can be a valuable tool for improving performance and productivity in Magento frontend development and PWA building.