Non-Blocking I/O is a method of input/output processing that allows a program to continue executing without waiting for an I/O operation to complete. This means that when a program requests data from a source, it can perform other tasks instead of being held up until the data is available. This approach is particularly useful in applications that require high responsiveness, such as web servers or real-time systems. In contrast to blocking I/O, where the program halts until the operation finishes, non-blocking I/O improves efficiency and resource utilization. It is commonly used in environments that handle multiple connections or tasks simultaneously, such as in Node.js or Java NIO. This allows developers to create more scalable and responsive applications.