The 'x64' file extension, while not directly representing a file format in the traditional sense, signifies that the file is an executable program compiled for a 64-bit architecture, specifically the x86-64 instruction set. These executables contain machine code instructions that the operating system's kernel can load into memory and execute. The x64 architecture is a superset of the older x86 (32-bit) architecture, offering increased addressable memory space and improved performance for many applications. An x64 executable typically contains code, data, and resources necessary for the program to function. The operating system's loader interprets the file's header information to determine how to allocate memory, load libraries, and start the program's execution. These files are crucial for running applications on modern 64-bit operating systems, enabling them to leverage the full capabilities of the hardware. The specific file format used for x64 executables varies depending on the operating system. On Windows, they are typically in the PE (Portable Executable) format, while on Linux and other Unix-like systems, they are usually in the ELF (Executable and Linkable Format) format. The 'x64' designation simply indicates the target architecture for the compiled code within the executable file.