In today's digital era, we find ourselves immersed in a vast landscape of mobile applications. But what about the "world's first app"? Determining this distinction isn't as straightforward as it might seem. The concept of apps has a long and complex history, evolving significantly over the years. To embark on our journey to uncover the world's first app, we must first define what we mean by an "app." An app, or application, refers to a software program created to perform specific tasks or functions on computers or mobile devices. In the early days of computing, applications were quite distinct from what we encounter today. The roots of software applications predate modern smartphone apps by several decades. Early recognized applications were predominantly linked to mainframe computers, serving specialized purposes such as scientific calculations, data processing, and even early video games. For instance, Fortran, which was developed in the late 1950s...