Paging

• Paging works by dividing a process--a computer program being executed--into blocks, known as pages, and loading the process pages into small, equally sized partitions, known as frames, in computer memory. Memory is allocated by the system, so paging is transparent to computer programmers.
  
  

Segmentation

• Segmentation allocates memory to specific functions inside sections of program code and so requires programmers to establish and maintain the segments. Memory is allocated in blocks of varying size, known as segments, according to the total amount required by a process.
  
  

Fragmentation

• Both paging and segmentation can cause fragmentation, or the breaking up of data stored in memory into chunks that are no longer contiguous (adjacent). Paging can allocate a page frame to a process that does not fill the whole frame, while segmentation can create segments that are not large enough to store an entire process.