If the executable is requested for execution,[b] then the operating system loads it into memory[3] and starts a process.[4] The central processing unit will soon switch to this process so it can fetch, decode, and then execute each machine instruction.[5] If the source code is requested for execution, then the operating system loads the corresponding interpreter into memory and starts a process. The interpreter then loads the source code into memory to translate and execute each statement. Running the source code is slower than running an executable.[6][c] Moreover, the interpreter must be installed on the computer.
