Network security level assessment: (referred to as "level assessment" for short) is an activity of assessment institutions to detect and evaluate the security level protection status of information systems that do not involve state secrets according to the national information security level protection system and relevant management norms and technical standards, and it is an important link of information system security level protection. Critical information infrastructure security detection and evaluation: (referred to as "critical information infrastructure security detection and evaluation") the activity of detecting and evaluating the security and possible risks of critical information infrastructure. The contents of detection and evaluation include but are not limited to the implementation of network security system (national and industry-related laws and regulations, policy documents and systems formulated by operators), organizational construction, personnel and funding investment, education and training, implementation of network security level protection, password application security evaluation, technical protection, cloud service security evaluation, risk evaluation, emergency drills, attack and defense drills, etc. Pay special attention to the cross-system and cross-regional information flow of key information infrastructure.