Answer:
The PATH Environment variable
Step-by-step explanation:
In computing, an environment variable refers an "object" that is dynamic and holds a value that is editable. This value is used by software programs running on the operating system to know what directories to; install files, find profiles of users, store temp files etc.
The PATH environment variable specifically handles the list of directories where executable programs can be found and it is useful as a security tool as well because every executing program or a session for a user will have its own unique PATH setting.