It is a contiguous part of the memory which is divided into a number of fixed and equal size pieces each of which is able to hold one piece of data.
Heap:
It is also a contiguous segment of memory but there is no restriction as to the size of different portions.
Text Segments:
This consists of program instructions, which the program must execute. For all users of a particular type of computer, this part of the process image is identical
Data Segments:
This is the part of the process image that stores the data that the program is working with. Each user’s data segments and stack will differ, even if they are all executing the same program.
Shared Memory Segments:
This is a part of the process image that provides the communication path between cooperating processes to share data or results among themselves.
Process Status Information:
This part of the process image stores the information about the process’s status. It is an important part as the operating system may decide to swap the information of the process from the main memory to the disk at any point of time.