Shared Memory Parallelization (done on same computer)

• loops are parallelized
• written in serial programming language
• user or compiler inserts directives (pragmas) into the code
• variables can be shared or private

Message Passing Interface (done on same or different computers)

• communication via special subroutine calls
• all variables are private
• parallelization done by programmer
• can require extensive code changes
• examples are MPI and PVM
• can be used on a wide variety of codes