End to End (E2E) Testing is a comprehensive testing methodology aimed at evaluating the entire application workflow, from start to finish, to ensure seamless integration with external interfaces and systems. This type of testing, which follows functional and system testing, is essential in the current Agile landscape where applications are often interconnected with multiple systems, making their flow complex. E2E testing assesses the health of back-end components, identifies errors in distributed environments, and validates application behavior in multi-tier systems, among other things. Although automation has limited scope in E2E testing due to the complexity and interconnectivity of modern applications, partial automation is feasible, particularly at the UI layer. The process faces challenges like managing workflows in distributed environments and access issues in offline applications, yet adhering to best practices such as risk analysis, scenario limitation, and environment management ensures effective testing. As technology advances, particularly with the growth of IoT, E2E testing is becoming increasingly significant in verifying the robustness of applications across all layers and interfaces.