Financial technology (Fintech) has emerged as a multidimensional phenomenon that refers to the intensive use of digital technologies in the provision of financial services and triggers structural transformations within the financial sector. This book chapter aims to examine the Fintech ecosystem from a comprehensive perspective by addressing the definition of Fintech, its historical development, key actors, core technologies employed, and its effects on the financial system in a holistic manner. Initially, the concept of Fintech was limited to the automation of banking transactions; however, particularly after the 2008 global financial crisis, it has evolved into a multi-layered and dynamic structure driven by accelerated digitalization, the development of entrepreneurial ecosystems, and the rise of user-oriented financial solutions. The Fintech ecosystem is shaped by the interaction of various stakeholders, including public authorities and regulatory bodies, traditional financial institutions, Fintech startups, technology providers, and users. These actors contribute to delivering financial services in a faster, more cost-effective, and accessible manner, while simultaneously enhancing competition and innovation within the sector. The core technologies utilized in the Fintech ecosystem include artificial intelligence, blockchain, data analytics, cloud computing, and mobile technologies. These technologies facilitate the emergence of new business models across a wide range of financial services, from payment systems and credit evaluation processes to investment advisory and insurance services. The effects of Fintech applications on the financial system are multidimensional, encompassing both opportunities and risks. On the one hand, Fintech enhances financial inclusion by enabling broader access to financial services; on the other hand, it raises new challenges such as data security, regulatory compliance, and systemic risks. In this context, ensuring a balance between innovation and regulation is of critical importance for the sustainable development of the Fintech ecosystem. Consequently, the Fintech ecosystem is considered a dynamic structure that shapes the future of the financial system.