The current mainstream mode of software development is the supply chain-level reuse of open-source software and components. It avoids repetitive development, reduces research and development costs, and enhances development efficiency. However, it inevitably brings about issues such as unknown component sources, unclear component compositions, unidentified component vulnerabilities, and license violations. To address these issues, researchers propose software bill of materials (SBOM). SBOM provides a detailed list of software components and their relationships, reveals potential and known threats, and makes software transparent. Since its proposal, research on SBOM by researchers both at home and abroad mainly focus on its current status, applications, and tools, lacking theoretical and systematic research. This study presents a comprehensive review of the background, basic concepts, generation techniques, tools and performance analysis, applications, challenges, and trends of SBOM. It also proposes the new concept of SBOM+, which integrates fine-grained security vulnerability perception and license conflict detection. The aim is to provide support for researchers engaged in SBOM, software development, and supply chain security from the perspectives of concepts, technologies, tools, applications, and development.