STDIO, or Standard Input/Output, is a fundamental concept in computing that allows programs to interact with users or other programs by reading input (usually from a keyboard or file) and writing output (typically to a display or file). In cybersecurity, understanding STDIO is important because attackers may exploit input/output streams to inject malicious commands or exfiltrate data. Command-line tools and scripts often use STDIO for automation and data processing. Secure handling of STDIO can help prevent vulnerabilities such as code injection and unauthorized data access, making it a key consideration in secure software development and system administration.