As the complexity of autonomous vehicles (AVs) continues to increase and artificial intelligence algorithms are becoming increasingly ubiquitous, a novel safety concern known as the safety of the intended functionality (SOTIF) has emerged, presenting significant challenges to the widespread deployment of AVs. SOTIF focuses on issues arising from the functional insufficiencies of the AVs' intended functionality or its implementation, apart from conventional safety considerations. From the systems engineering standpoint, this study offers a comprehensive exploration of the SOTIF landscape by reviewing academic research, practical activities, challenges, and perspectives across the development, verification, validation, and operation phases. Academic research encompasses system-level SOTIF studies and algorithm-related SOTIF issues and solutions. Moreover, it encapsulates practical SOTIF activities undertaken by corporations, government entities, and academic institutions spanning international and Chinese contexts, focusing on the overarching methodologies and practices in different phases. Finally, the paper presents future challenges and outlook pertaining to the development, verification, validation, and operation phases, motivating stakeholders to address the remaining obstacles and challenges.