Environment variables are placeholders for data that can change. Each user has its own environment variables with different values that define his working environment. For example, each user typically has its own home directory, so the content of the HOMEPATH environment variable is different for each user on the system.
The environment variables associated with the selected process are listed under the Environment tab:
Most often, the processes inherit their environment variables from their parent process, and the environment variables of all processes will be the same. However, there are exceptions: a parent process can specify a different set of environment variables for a child process or each process can add, delete, or modify its own environment variables.