A (often called a "crack" or "fixed executable") is a modified version of the game's main .exe file. Developers of these mods reverse-engineer the game code to remove the instruction that tells the program to look for a physical disc. By replacing the original speed.exe with this modified version, the game runs directly from the hard drive, no disc required.
Right-click the new speed.exe -> Properties -> Compatibility tab: need for speed most wanted nocd mod
The NoCD mod is not just a workaround; it is the for the entire NFS MW modding ecosystem. Once you remove the DRM, you unlock the ability to apply massive overhauls: A (often called a "crack" or "fixed executable")