Fclose is a function used in programming, particularly in languages like C and C++, to close a file that has been opened for reading or writing. When a file is closed using Fclose, it ensures that all data is properly saved and resources are released, preventing memory leaks and other issues. Using Fclose is essential for maintaining the integrity of data and system performance. It is typically called after all file operations are completed, signaling to the operating system that the file is no longer needed. This practice helps in managing file access and ensuring that other processes can use the file if necessary.