Digital twins can be defined as a virtual representation of a physical object that can replicate its behavior in a virtual environment. This concept involves the integration of three distinct components: the physical space, the virtual space, and the communication between these two spaces. Digital twins are recognized as one of the key driving forces in various industries, and a comprehensive understanding is necessary to utilize them. A thorough review of the advantages and disadvantages of digital twins, including their value, characteristics, applications, and challenges, is essential to analyze their growth potential and investment value. This paper comprehensively reviews the digital twin applications being studied across industries. To this end, we propose three research questions and address them through a structured literature review. First, we examine the core technologies of digital twins and find that they form an integrated framework combining modeling, sensing, and real-time data processing. Second, we analyze their adoption across industries and observe widespread use in aerospace and aeronautics, manufacturing, healthcare, energy, and urban systems with domain-specific objectives. Third, we explore life-cycle applications and identify digital twins as enablers of continuity from design to operation and evolution. These findings offer a broad perspective on the current state and future potential of digital twin applications.