This article provides an overview of the concept of optical orbital angular momentum (OAM), a topic of significant research interest in the field of optics. The paper discusses the historical development of OAM, starting with the foundational work by Allen, Beijersbergen, Spreeuw, and Woerdman in 1992, and highlights the subsequent advancements in both theoretical and experimental studies over the past three decades. It emphasizes the importance of OAM in various applications, including optical communications, microscopy, and optical trapping. The paper also includes a tribute to Les Allen, a key figure in the development of OAM research, and reflects on his contributions to the field. The article outlines the significance of OAM in both classical and quantum optics, noting its potential for use in information processing and communication. It also touches on the broader implications of OAM in other areas of physics, such as electron vortices and chiral interactions. The paper concludes with a reflection on the impact of OAM research and its future potential.This article provides an overview of the concept of optical orbital angular momentum (OAM), a topic of significant research interest in the field of optics. The paper discusses the historical development of OAM, starting with the foundational work by Allen, Beijersbergen, Spreeuw, and Woerdman in 1992, and highlights the subsequent advancements in both theoretical and experimental studies over the past three decades. It emphasizes the importance of OAM in various applications, including optical communications, microscopy, and optical trapping. The paper also includes a tribute to Les Allen, a key figure in the development of OAM research, and reflects on his contributions to the field. The article outlines the significance of OAM in both classical and quantum optics, noting its potential for use in information processing and communication. It also touches on the broader implications of OAM in other areas of physics, such as electron vortices and chiral interactions. The paper concludes with a reflection on the impact of OAM research and its future potential.