API testing, also known as Application Programming Interface testing, has become increasingly important in recent years due to its role in ensuring seamless communication between applications without human intervention. APIs act as bridges that allow different software systems to interact, enabling features like "Login with Google" and aggregating data from multiple sources on platforms like Trivago. The growth of agile practices and the Internet of Things (IoT) has driven the need for effective API testing, as it provides prompt feedback and supports continuous integration. API testing encompasses various types, including functional, reliability, load, stress, security, integration, and usability testing, each ensuring that APIs perform correctly under different conditions. According to Mike Cohn's test pyramid model, API tests, positioned in the middle layer, should be automated more frequently than GUI tests because they run faster and are integral to maintaining robust application functionality. The emphasis on API testing highlights its critical role in application development, where smooth inter-application communication is essential.