Final answer:
Python's sys library is used to interact with the interpreter, with common uses including retrieval of command-line arguments via sys.argv, script termination via sys.exit(), and manipulating the standard input/output/error streams.
Step-by-step explanation:
A common use of Python's sys library is to interact with the interpreter. The sys module provides functions and variables used to manipulate different parts of the Python runtime environment. For example, sys.argv is used to retrieve command-line arguments passed to a script.
This is particularly useful for scripts intended to be used as command-line utilities. Additionally, sys.exit() allows a script to terminate its execution.
There are other applications such as accessing the list of path directories in which Python looks for modules (sys.path), getting the maximum integer value a variable can take (sys.maxsize), and dealing with the standard input/output/error streams (sys.stdin, sys.stdout, and sys.stderr).