A syscall, or system call, is a fundamental mechanism that allows user-level programs to interact with the operating system's kernel. When a program needs to perform low-level operations - such as reading from a file, writing to a device, or allocating memory - it cannot do so directly due to security and stability concerns. Instead, it issues a syscall, which is a controlled request for the kernel to perform the operation on its behalf. Syscalls form the interface between user applications and the core functions of the operating system, ensuring that resources are managed securely and efficiently. In cybersecurity, syscalls are often monitored, as malicious software may use them to perform unauthorized actions or escalate privileges.